UP Board Class 10 Science Question Paper 2023 (Code 824 EM) Available- Download Here with Solution PDF

In a lens, the optical centre is the point at which light rays pass through without deviation. It is the central point of the lens and is where no refraction occurs for light passing through it.

Step 1: Focus.

The focus is the point where parallel rays of light converge after passing through the lens. A light ray passing through the focus will not pass without deviation.

Step 2: Centre of curvature.

The centre of curvature is a point related to the spherical surface of the lens. Light rays passing through the centre of curvature do not pass through the lens without deviation.

Step 3: Optical centre.

The optical centre is the point inside the lens where a light ray passes through without any deviation. This is the correct answer.


Step 4: Conclusion.

Thus, the correct answer is (C) Optical centre.
Quick Tip: The optical centre of a lens is the point through which light passes without any deviation.

When a light ray passes through the centre of curvature of a concave mirror, it strikes the mirror’s surface perpendicularly. Since the incident ray is perpendicular to the surface, the angle of incidence is 0°. According to the law of reflection, the angle of reflection is equal to the angle of incidence. Hence, the angle of reflection is also 0°.

Step 1: Angle of incidence.

The angle of incidence is the angle between the incident ray and the normal to the mirror's surface. Since the ray passes through the centre of curvature, this angle is 0°.

Step 2: Angle of reflection.

According to the law of reflection, the angle of reflection is equal to the angle of incidence. Therefore, the angle of reflection is 0°.

Step 3: Conclusion.

Thus, the correct answer is (C) 0°.
Quick Tip: When a light ray passes through the centre of curvature of a concave mirror, the angle of incidence and angle of reflection are both 0°.

The normal eye can clearly see objects that are within a specific range. This range is between the near point (approximately 25 cm) and infinity. The near point is the closest distance at which the eye can focus on an object, and the far point is at infinity for a normal eye.


Step 1: Understanding the near point and far point.

For a normal human eye, the near point is around 25 cm (the closest distance at which a person can clearly see an object). The far point is infinity, meaning the eye can clearly see objects at any distance beyond 25 cm.


Step 2: Analysis of Options.

- (A) in between 50 cm and 100 m: This is incorrect because the normal eye can see objects closer than 50 cm (around 25 cm).

- (B) in between 25 cm and infinity: This is correct because the normal eye can clearly see objects in this range.

- (C) in between 100 cm and 1000 m: This is incorrect because the normal eye can see objects as close as 25 cm.

- (D) in between 25 cm and 150 cm: This is incorrect because the range of vision is much broader for a normal eye.


Step 3: Conclusion.

The correct answer is (B) in between 25 cm and infinity.
Quick Tip: The normal human eye can clearly see objects at distances between 25 cm and infinity.

According to Ohm's Law, the current \(I\) in a circuit is related to the potential difference \(V\) and the resistance \(R\) by the equation:
\[ I = \frac{V}{R} \]

When the potential difference \(V\) is constant, the current is inversely proportional to the resistance. If the resistance is tripled, the current will decrease by a factor of 3.

Step 1: Tripling the resistance.

If the resistance \(R\) is tripled, the new current \(I'\) is given by:
\[ I' = \frac{V}{3R} \]

Step 2: Comparing with original current.

Since \(I = \frac{V}{R}\), the new current \(I'\) will be:
\[ I' = \frac{1}{3} I \]

Thus, the current will become one-third of its original value.


Step 3: Conclusion.

The correct answer is (B) one-fourth because the current is inversely proportional to resistance, and tripling the resistance results in a current decrease.
Quick Tip: The current in a circuit is inversely proportional to the resistance when the potential difference is constant.

The power consumed by an electric bulb is given by the formula: \[ P = \frac{V^2}{R} \]
where \(P\) is the power, \(V\) is the voltage, and \(R\) is the resistance of the bulb.

Step 1: Power consumed by the first bulb (100 \(\Omega\)):

For the first bulb, resistance \(R_1 = 100 \, \Omega\), and the voltage supplied is \(V = 200 \, V\). \[ P_1 = \frac{(200)^2}{100} = \frac{40000}{100} = 400 \, W \]
This is the power consumed by the first bulb in 1 hour.

Step 2: Power consumed by the second bulb (200 \(\Omega\)):

For the second bulb, resistance \(R_2 = 200 \, \Omega\), and the voltage supplied is \(V = 200 \, V\). \[ P_2 = \frac{(200)^2}{200} = \frac{40000}{200} = 200 \, W \]
This is the power consumed by the second bulb in 1 hour.

Step 3: Total power consumption.

The total power consumption is the sum of the power consumed by both bulbs: \[ P_{total} = P_1 + P_2 = 400 \, W + 200 \, W = 600 \, W \]
This is the total power consumed in 1 hour. The total energy consumption in watt-hours (Wh) is: \[ E = P_{total} \times t = 600 \, Wh \]

Step 4: Conclusion.

The total power consumed daily by both bulbs is 600 Wh, which corresponds to option (B).
Quick Tip: To calculate energy consumption, use the formula \( E = P \times t \), where \(P\) is power in watts, and \(t\) is time in hours.

In optics, the focal length (\(f\)) of a mirror or lens determines how it focuses light. The sign of the focal length indicates the type of mirror or lens:

- For concave mirrors and concave lenses, the focal length is negative.
- For convex mirrors and convex lenses, the focal length is positive.

Step 1: Focal length of the mirror.

Given that the focal length of the spherical mirror is -25 cm, this indicates that it is a concave mirror (since concave mirrors have negative focal lengths).

Step 2: Focal length of the lens.

Similarly, the focal length of the lens is also -25 cm, which indicates that the lens is concave (since concave lenses have negative focal lengths).

Step 3: Conclusion.

Therefore, both the mirror and the lens are concave. The correct answer is (D) both concave.
Quick Tip: Concave mirrors and concave lenses have negative focal lengths, while convex mirrors and convex lenses have positive focal lengths.

When resistors are connected in series, the current flowing through them is the same, and the potential difference across each resistor is determined by Ohm's law:
\[ V = I \times R \]

Where \(V\) is the potential difference, \(I\) is the current, and \(R\) is the resistance.

Step 1: Calculate the potential difference across each resistor.


- For the first resistor of \(2 \, \Omega\), the potential difference is: \[ V_1 = 2 \, A \times 2 \, \Omega = 4 \, V \]

- For the second resistor of \(4 \, \Omega\), the potential difference is: \[ V_2 = 2 \, A \times 4 \, \Omega = 8 \, V \]

- For the third resistor of \(6 \, \Omega\), the potential difference is: \[ V_3 = 2 \, A \times 6 \, \Omega = 12 \, V \]

Step 2: Analyze the options.

The potential differences at the ends of the resistances will be \( 4 \, V, 8 \, V, 12 \, V \), corresponding to option (A).


Step 3: Conclusion.

The correct order of potential differences at the ends of these resistances is \( 4 \, V, 8 \, V, 12 \, V \). The correct answer is (A).
Quick Tip: The potential difference across resistors in series is determined by Ohm's law \(V = I \times R\), and the current remains the same through all resistors.

This reaction involves zinc (Zn) displacing hydrogen (H) from sulfuric acid (H\(_2\)SO\(_4\)), forming zinc sulfate (ZnSO\(_4\)) and hydrogen gas (\(H_2\)). This is a classic example of a displacement reaction, where one element displaces another from a compound.


Step 1: Combination reaction.

A combination reaction is one where two or more substances combine to form a single product. This does not apply here, so option (A) is incorrect.


Step 2: Displacement reaction.

In a displacement reaction, a more reactive element displaces a less reactive element from its compound. Here, zinc displaces hydrogen from sulfuric acid, forming zinc sulfate and hydrogen gas. Therefore, option (B) is correct.


Step 3: Decomposition reaction.

A decomposition reaction involves the breakdown of a compound into simpler substances, which does not occur in this reaction. So, option (C) is incorrect.


Step 4: Double displacement reaction.

A double displacement reaction involves the exchange of ions between two compounds, which is not the case here. Therefore, option (D) is incorrect.


Step 5: Conclusion.

The correct type of reaction is a displacement reaction, so the correct answer is (B).
Quick Tip: In a displacement reaction, a more reactive element displaces a less reactive element from its compound.

Sodium carbonate \( Na_2CO_3 \) is commonly known as washing soda. It is used in cleaning and washing processes because it can soften water.


Step 1: Bleaching powder.

Bleaching powder is \( Ca(OCl)_2 \), which is used for bleaching purposes and is not related to \( Na_2CO_3 \).


Step 2: Baking powder.

Baking powder is a mixture of sodium bicarbonate \( NaHCO_3 \) and an acid. It is not the same as washing soda.


Step 3: Plaster of Paris.

Plaster of Paris is \( CaSO_4 \cdot \frac{1}{2} H_2O \), and it is used for making molds, not for cleaning purposes like washing soda.


Step 4: Conclusion.

Therefore, the correct answer is (C) Washing soda.
Quick Tip: Sodium carbonate \( Na_2CO_3 \) is commonly known as washing soda and is used in laundry to soften water.

Alkali metals are a group of elements in the periodic table that belong to group 1. These metals are highly reactive and include:
- Sodium (Na)
- Potassium (K)
- Lithium (Li)
- Rubidium (Rb)
- Cesium (Cs)
- Francium (Fr)


Step 1: Sodium (Na).

Sodium (Na) is an alkali metal and belongs to group 1 of the periodic table.


Step 2: Iron (Fe).

Iron (Fe) is a transition metal and does not belong to the alkali metal group.


Step 3: Magnesium (Mg).

Magnesium (Mg) is an alkaline earth metal, not an alkali metal.


Step 4: Gold (Au).

Gold (Au) is a transition metal, and like iron, it is not an alkali metal.


Step 5: Conclusion.

Thus, the correct answer is (A) Na (Sodium).
Quick Tip: Alkali metals are in group 1 of the periodic table and include sodium (Na), lithium (Li), potassium (K), and others.

Matching the compounds:

- a. Haloalkane: A haloalkane has a halogen (Cl, Br, I, etc.) attached to a carbon atom. The correct example from Column B is ii, which is \( H-C-C-C-Cl \) (Chloroalkane).

- b. Alcohol: An alcohol contains a hydroxyl group (-OH) attached to a carbon atom. The correct example from Column B is i, which is \( H-C-C-OH \) (Ethanol).

- c. Ketone: A ketone contains a carbonyl group (C=O) attached to two carbon atoms. The correct example from Column B is iv, which is \( H-C-C=C-H \) (Acetone).

- d. Alkene: An alkene has a carbon-carbon double bond. The correct example from Column B is iii, which is \( H-C-C-C-H \) (Propene).



Conclusion:

The correct matching is: \[ \boxed{A \, a - ii, \, b - i, \, c - iv, \, d - iii} \] Quick Tip: A hydroxyl group (-OH) indicates alcohol, a carbonyl group (C=O) indicates a ketone, and the presence of a halogen (like Cl) indicates a haloalkane.

Alkali metals are a group of elements found in Group 1 of the periodic table. They are characterized by having one electron in their outermost shell, which makes them highly reactive, especially with water. The alkali metals include:


- Lithium (Li)

- Sodium (Na)

- Potassium (K)


These elements are known for their strong reactivity and their ability to form basic (alkaline) solutions when combined with water. Therefore, option (B) is correct.


Step 1: Be, Mg, Ca.

Beryllium (Be), Magnesium (Mg), and Calcium (Ca) are alkaline earth metals, which are in Group 2 of the periodic table, not alkali metals. So, option (A) is incorrect.


Step 2: B, Al, Ga.

Boron (B), Aluminum (Al), and Gallium (Ga) are elements in Group 13 of the periodic table, which are not alkali metals. Therefore, option (C) is incorrect.


Step 3: Cu, Ag, Au.

Copper (Cu), Silver (Ag), and Gold (Au) are transition metals, not alkali metals. Therefore, option (D) is incorrect.


Step 4: Conclusion.

The correct alkali metals are Li, Na, and K. The correct answer is (B).
Quick Tip: Alkali metals are found in Group 1 of the periodic table and include elements like lithium (Li), sodium (Na), and potassium (K).

Alkynes are hydrocarbons that contain a triple bond between two carbon atoms. The general formula for alkynes is: \[ C_n H_{2n-2} \]
where \( n \) is the number of carbon atoms in the molecule. This formula reflects the fact that alkynes are unsaturated hydrocarbons with two fewer hydrogen atoms compared to alkanes (which follow the formula \( C_n H_{2n+2} \)) and alkenes (which follow the formula \( C_n H_{2n} \)).


Step 1: Analyzing option (A).

Option (A) \( C_n H_{2n} \) is the formula for alkanes, not alkynes.


Step 2: Analyzing option (B).

Option (B) \( C_n H_{2n+2} \) is the formula for alkanes, not alkynes.


Step 3: Analyzing option (D).

Option (D) \( C_{n+2} H_{2n} \) is not the correct formula for any specific type of hydrocarbon.


Step 4: Conclusion.

Thus, the correct formula for alkynes is (C) \( C_n H_{2n-2} \).
Quick Tip: Alkynes are unsaturated hydrocarbons with a triple bond and follow the formula \( C_n H_{2n-2} \).

Water and minerals absorbed by the roots of plants are transported through the plant by a vascular tissue known as xylem. Xylem conducts water and dissolved minerals from the roots to the rest of the plant, including the leaves where it is used in photosynthesis.


Step 1: Phloem.

Phloem is responsible for transporting the products of photosynthesis, mainly sugars, from the leaves to other parts of the plant. It does not transport water or minerals.


Step 2: Stomata.

Stomata are pores in the leaves through which gas exchange (such as oxygen and carbon dioxide) occurs. They do not transport water or minerals.


Step 3: Cambium.

Cambium is a type of meristematic tissue that is responsible for the secondary growth of plants (growth in thickness). It does not transport water or minerals.


Step 4: Conclusion.

Thus, the correct tissue responsible for transporting water and minerals in plants is (A) Xylem.
Quick Tip: Xylem transports water and minerals from the roots to the rest of the plant.

Blood pressure is the force of blood against the walls of the arteries as the heart pumps it around the body. The normal blood pressure for a healthy adult human is typically 120/80 mmHg. The first number (120) represents the systolic pressure, or the pressure when the heart beats, while the second number (80) represents the diastolic pressure, or the pressure when the heart rests between beats.


Step 1: 140/90.

A blood pressure of 140/90 mmHg is considered to be in the high blood pressure (hypertension) range. Therefore, option (A) is incorrect.


Step 2: 140/100.

A blood pressure of 140/100 mmHg is also considered to be high blood pressure (hypertension), making option (B) incorrect.


Step 3: 120/80.

A blood pressure of 120/80 mmHg is the standard value for normal, healthy blood pressure. Therefore, option (C) is correct.


Step 4: 150/85.

A blood pressure of 150/85 mmHg is considered to be elevated, but not as high as hypertension stage 2. So, option (D) is also incorrect.


Step 5: Conclusion.

The normal blood pressure is 120/80 mmHg. The correct answer is (C).
Quick Tip: A normal blood pressure for a healthy adult is 120/80 mmHg. High blood pressure is considered to be 140/90 mmHg or higher.

Homologous organs are those that have a similar structure but may have different functions. These organs arise from a common ancestor, indicating evolutionary divergence. The wings of birds and the forelimbs of mammals are homologous organs because both have the same basic bone structure but serve different functions (flying in birds and grasping or walking in mammals).


Step 1: Wings of bats and birds.

Although bats and birds both have wings, their wings are not homologous. They evolved independently, so this is not a good example of homologous organs. Therefore, option (A) is incorrect.


Step 2: Wings of birds and forelimbs of mammals.

The wings of birds and the forelimbs of mammals are homologous organs. They share a similar bone structure but serve different functions, making this the correct answer.


Step 3: Wings of birds and insects.

The wings of birds and insects are analogous organs, not homologous. They have different evolutionary origins and structures. Therefore, option (C) is incorrect.


Step 4: Wings of insects and bats.

The wings of insects and bats are also analogous organs. Although they both have wings, these structures evolved independently and have different underlying structures, so option (D) is incorrect.


Step 5: Conclusion.

The best example of homologous organs is the wings of birds and the forelimbs of mammals. The correct answer is (B).
Quick Tip: Homologous organs have a similar structure due to shared ancestry but may have different functions.

According to Mendel's laws of inheritance, the genotype for the tall stem is represented by the dominant allele \( T \), and the genotype for the wrinkled seeds is represented by the recessive allele \( r \). Therefore, the correct genotype for expressing tall stem and wrinkled seeds must have at least one dominant \( T \) and two recessive \( r \) alleles. The genotype that fits this requirement is \( TTrr \).


Step 1: Analyzing option (A).

Option (A) \( TTRR \) would express tall stems and round seeds, as both traits are controlled by dominant alleles.


Step 2: Analyzing option (B).

Option (B) \( ttRR \) would express short stems and round seeds, as the stem length is controlled by the \( T \) allele and the seed shape is controlled by the \( R \) allele.


Step 3: Analyzing option (D).

Option (D) \( ttrr \) would express short stems and wrinkled seeds, as both traits are controlled by recessive alleles.


Step 4: Conclusion.

Thus, the correct genotype for tall stems and wrinkled seeds is (C) \( TTrr \).
Quick Tip: Mendel's laws of inheritance state that dominant alleles mask the expression of recessive alleles, leading to the phenotypic expression of dominant traits.

Binary fission is a type of asexual reproduction in which a single organism divides into two identical offspring. This process occurs in unicellular organisms such as Amoeba. During binary fission, the nucleus of the amoeba divides, followed by the division of the cytoplasm, resulting in two new organisms.


Step 1: Plasmodium.

Plasmodium, the parasite responsible for malaria, undergoes both sexual and asexual reproduction, but its asexual reproduction occurs through a different method called schizogony, not binary fission.


Step 2: Bryophyllum.

Bryophyllum is a plant that reproduces asexually through vegetative propagation, not binary fission. It produces plantlets from the leaves.


Step 3: Potato.

Potato reproduces asexually through tubers, not by binary fission.


Step 4: Conclusion.

Thus, the correct answer is (A) Amoeba, as it reproduces by binary fission.
Quick Tip: Binary fission is a type of asexual reproduction that occurs in unicellular organisms such as Amoeba.

The Chipko Movement, which aimed at protecting forests from deforestation, was started in the Garhwal area of the Himalayas in the 1970s. The local villagers, particularly women, hugged trees to prevent them from being felled, thus the name "Chipko" (meaning "to hug" in Hindi). This movement played a significant role in raising awareness about environmental conservation. Therefore, option (A) is correct.


Step 1: Aravali area of Rajasthan.

The Aravalli region is an important mountain range, but the Chipko movement was not started there. Therefore, option (B) is incorrect.


Step 2: Nilgiri area of South India.

While the Nilgiri hills are important for biodiversity, the Chipko Movement was not initiated in this region. Therefore, option (C) is incorrect.


Step 3: Madhya Pradesh.

Madhya Pradesh is an important state for forest conservation, but it was not the birthplace of the Chipko Movement. Therefore, option (D) is incorrect.


Step 4: Conclusion.

The Chipko Movement began in the Garhwal area of the Himalayas. The correct answer is (A).
Quick Tip: The Chipko Movement, started in the Garhwal area of the Himalayas, is a great example of grassroots environmental activism.

Gastric glands are specialized glands located in the stomach. These glands secrete gastric juice, which contains hydrochloric acid (HCl) and enzymes like pepsin, which help in the digestion of food. Therefore, option (B) is correct.


Step 1: Small intestine.

The small intestine is the site of nutrient absorption, but gastric glands are not located there. The secretion of digestive enzymes occurs in the small intestine, but the gastric glands are found in the stomach. So, option (A) is incorrect.


Step 2: Pancreas.

The pancreas secretes pancreatic juices that contain digestive enzymes, but it does not contain gastric glands. Therefore, option (C) is incorrect.


Step 3: Large intestine.

The large intestine is involved in water absorption and the formation of feces, but it does not have gastric glands. Therefore, option (D) is incorrect.


Step 4: Conclusion.

The gastric glands are located in the stomach. The correct answer is (B).
Quick Tip: Gastric glands secrete digestive juices in the stomach that help in breaking down food.

There are two types of spherical mirrors:

1. Concave mirror: A mirror with an inward-curved reflecting surface.

2. Convex mirror: A mirror with an outward-curved reflecting surface.


Centre of Curvature and Principal Axis:

- Centre of Curvature (C): The centre of the sphere of which the mirror is a part. It lies on the principal axis.

- Principal Axis: The line passing through the centre of curvature and the pole of the mirror. It is the axis of symmetry of the mirror.


For the given convex mirror:

- Focal length (f): 30 cm (given)

- The object distance (\(u\)) = -30 cm (object is in front of the mirror)

- The object height = 5 cm (given)


Using the mirror formula:
\[ \frac{1}{f} = \frac{1}{v} + \frac{1}{u} \]
Substituting the values:
\[ \frac{1}{30} = \frac{1}{v} + \frac{1}{-30} \]

Solving for \(v\):
\[ \frac{1}{v} = \frac{1}{30} + \frac{1}{30} = \frac{2}{30} = \frac{1}{15} \]

Therefore, \(v = 15 \, cm\).


The image is formed at a distance of 15 cm behind the mirror, indicating that it is a virtual image. Since the image is formed behind the mirror, the image will be diminished and erect.



Conclusion:

The image formed by the convex mirror is virtual, diminished, and erect, with a position 15 cm behind the mirror.
Quick Tip: In convex mirrors, the image formed is always virtual, erect, and smaller than the object, regardless of the object distance.

The power of accommodation refers to the ability of the eye to focus on objects at varying distances by changing the shape of the eye's lens. The eye can adjust its focus from distant objects to near objects through this accommodation process. The ciliary muscles control the shape of the lens to adjust the focal length, allowing the eye to focus on both near and far objects.


Ray Diagrams for Convex Lens:

1. When the object is at a distance of 2f:

For this case, the image formed by a convex lens will be real, inverted, and of the same size as the object. The image is formed at a distance of 2f.


\begin{tikzpicture
% Convex Lens
\draw[thick] (0,0) ellipse (0.2 and 1); % lens
\node at (0,1.2) {Convex Lens;

% Focal points
\node at (2,-0.2) {2f;
\node at (3, 0.5) {Image;

% Object
\node at (-3, 1.5) {Object;
\draw[->] (-2, 1.5) -- (0, 0); % Ray 1
\draw[->] (-2, 0.8) -- (2, 0.8); % Ray 2
\draw[->] (0, 0) -- (1.5, -1); % Ray 3

\end{tikzpicture

2. When the object is between 2f and infinity:

In this case, the image formed is real, inverted, and diminished in size. The image position lies between f and 2f.


\begin{tikzpicture
% Convex Lens
\draw[thick] (0,0) ellipse (0.2 and 1); % lens
\node at (0,1.2) {Convex Lens;

% Focal points
\node at (2,-0.2) {f;
\node at (4,-0.2) {2f;
\node at (3, 0.5) {Image;

% Object
\node at (-3, 1.5) {Object;
\draw[->] (-2, 1.5) -- (0, 0); % Ray 1
\draw[->] (-2, 0.8) -- (3, 0.8); % Ray 2
\draw[->] (0, 0) -- (2.5, -1); % Ray 3

\end{tikzpicture


Conclusion:

1. Power of accommodation: The ability of the eye to focus on objects at different distances by changing the shape of the lens.

2. Convex lens ray diagrams:
- When the object is at 2f, the image is real, inverted, and of the same size.

- When the object is between 2f and infinity, the image is real, inverted, and diminished.
Quick Tip: The focal length of the eye's lens changes as it accommodates for near or far vision, allowing clear images to form on the retina.

Advantages of Parallel Combination of Resistances:

1. Constant Voltage:

In a parallel combination, the voltage across each resistance is the same. This ensures that each device or component receives the same voltage, which is often required for uniform operation.


2. Effective Resistance Decreases:

In a parallel combination, the total or equivalent resistance decreases as more resistances are added. This allows for more efficient current flow through the circuit. The total resistance is always lower than the smallest resistance in the combination.


Given:

- Resistances: \( R_1 = 8 \, \Omega \), \( R_2 = 12 \, \Omega \), and \( R_3 = 24 \, \Omega \)

- Voltage: \( V = 8 \, V \)

- The resistors are in parallel, so the total resistance \( R_{eq} \) can be calculated using the formula: \[ \frac{1}{R_{eq}} = \frac{1}{R_1} + \frac{1}{R_2} + \frac{1}{R_3} \]
Substituting the values: \[ \frac{1}{R_{eq}} = \frac{1}{8} + \frac{1}{12} + \frac{1}{24} \]
Finding the LCM of the denominators: \[ \frac{1}{R_{eq}} = \frac{3}{24} + \frac{2}{24} + \frac{1}{24} = \frac{6}{24} = \frac{1}{4} \]
Thus, the total resistance: \[ R_{eq} = 4 \, \Omega \]

Total Current in the Circuit:

Using Ohm’s law, the total current \( I \) is given by: \[ I = \frac{V}{R_{eq}} = \frac{8}{4} = 2 \, A \]

Current in Each Resistance:

Since the resistances are in parallel, the current in each resistor can be calculated using Ohm’s law: \[ I_1 = \frac{V}{R_1} = \frac{8}{8} = 1 \, A \] \[ I_2 = \frac{V}{R_2} = \frac{8}{12} = \frac{2}{3} \, A \] \[ I_3 = \frac{V}{R_3} = \frac{8}{24} = \frac{1}{3} \, A \]


Conclusion:

The total current in the circuit is \( 2 \, A \). The current through each resistor is:
- \( I_1 = 1 \, A \) through the 8 \( \Omega \) resistor

- \( I_2 = \frac{2}{3} \, A \) through the 12 \( \Omega \) resistor

- \( I_3 = \frac{1}{3} \, A \) through the 24 \( \Omega \) resistor
Quick Tip: In parallel circuits, the total current is the sum of the currents through each branch, and the voltage across all resistors is the same.

Electromagnetic Induction:

Electromagnetic induction is the process of generating an electric current in a conductor by changing the magnetic field around it. This phenomenon was discovered by Michael Faraday in 1831. When a conductor (such as a coil of wire) moves through a magnetic field or when the magnetic field around the conductor changes, an electric current is induced in the conductor. The induced current can be produced by either of the following methods:

Methods of Producing Induced Current:

1. Moving a Conductor Through a Magnetic Field:

When a conductor moves through a magnetic field, the magnetic flux through the conductor changes, which induces a current. The greater the speed of movement, the greater the induced current.

2. Changing the Magnetic Field Around a Coil:

If a magnetic field around a stationary coil changes (e.g., by moving a magnet in and out of the coil or changing the strength of the magnetic field), a current is induced in the coil due to the change in magnetic flux.

Fleming's Right Hand Rule:

Fleming’s Right Hand Rule is used to determine the direction of the induced current when a conductor moves through a magnetic field. The rule states that:

- Hold the right hand with the thumb, index, and middle fingers perpendicular to each other.

- The thumb represents the direction of the motion of the conductor (moving through the magnetic field).

- The index finger represents the direction of the magnetic field (from North to South).

- The middle finger represents the direction of the induced current in the conductor.



Conclusion:

Electromagnetic induction is an important principle in the generation of electric power. The methods of producing induced current, such as moving a conductor through a magnetic field or changing the magnetic field around a coil, form the basis for technologies like electric generators and transformers. Fleming's right-hand rule helps determine the direction of the induced current. Quick Tip: When dealing with electromagnetic induction, always use Fleming’s right-hand rule to find the direction of the induced current in a conductor moving through a magnetic field.

Use of an Electric Motor:

An electric motor is a device that converts electrical energy into mechanical energy through the interaction of magnetic fields and electric currents. It is widely used in various appliances and machinery, such as fans, refrigerators, washing machines, and industrial machines.

Construction of an Electric Motor:

The main components of an electric motor include:
1. Armature:

A coil of wire that rotates within the magnetic field. It is attached to a shaft that rotates to produce mechanical motion.

2. Magnet:

The permanent magnet or electromagnet provides the magnetic field in which the armature rotates.

3. Commutator:

A split ring that reverses the direction of the current in the armature coil at regular intervals to ensure continuous rotation.

4. Brushes:

These are made of carbon and maintain electrical contact with the rotating armature coil.

5. Power Source:

The external source of electrical energy that supplies the motor with current.

Working Principle:

The working of an electric motor is based on the principle that when a current-carrying conductor is placed in a magnetic field, it experiences a force (Lorentz force). The direction of the force is given by Fleming's Left-Hand Rule. The force on the armature causes it to rotate, converting electrical energy into mechanical energy.

Working of an Electric Motor:

- When current flows through the armature, it creates a magnetic field around the coil. This interacts with the external magnetic field, producing a force on the armature that causes it to rotate.

- As the armature rotates, the commutator reverses the direction of current flow in the coil at appropriate intervals to keep the armature rotating in the same direction.

- The mechanical energy produced by the rotating armature is used to drive the external machinery connected to the motor.



Conclusion:

An electric motor is essential for converting electrical energy into mechanical work in many devices. Its construction involves components like the armature, magnet, commutator, and brushes, and its working principle revolves around the interaction of magnetic fields and electric currents. Quick Tip: Electric motors are integral in converting electrical energy into mechanical energy, used in everyday appliances and industrial machines.

(i) Balancing the first equation:

The given equation is: \[ H_2SO_4 (aq) + NaOH (aq) \rightarrow Na_2SO_4 (aq) + H_2O (l) \]

- Balance the number of sodium (Na) atoms: There are 2 Na atoms in \( Na_2SO_4 \), so we need 2 NaOH on the left.

- Balance the hydrogen (H) atoms: There are 2 H atoms in \( H_2SO_4 \) and 2 NaOH, so hydrogen is balanced.

- The sulfur (S) and oxygen (O) atoms are already balanced.


Thus, the balanced equation is: \[ H_2SO_4 (aq) + 2NaOH (aq) \rightarrow Na_2SO_4 (aq) + 2H_2O (l) \]



(ii) Balancing the second equation:

The given equation is: \[ MgCl_2 (aq) + 2AgNO_3 (aq) \rightarrow Mg(NO_3)_2 (aq) + 2AgCl (g) \]

- Balance the magnesium (Mg) atoms: One Mg atom on both sides.

- Balance the chlorine (Cl) atoms: 2 \( Cl \) atoms on both sides.

- Balance the silver (Ag) atoms: 2 \( Ag \) atoms on both sides.

- Balance the nitrate (NO₃) ions: 2 \( NO_3 \) ions on both sides.


Thus, the balanced equation is: \[ MgCl_2 (aq) + 2AgNO_3 (aq) \rightarrow Mg(NO_3)_2 (aq) + 2AgCl (g) \]


Conclusion:

The balanced equations are:
1. \( H_2SO_4 (aq) + 2NaOH (aq) \rightarrow Na_2SO_4 (aq) + 2H_2O (l) \)

2. \( MgCl_2 (aq) + 2AgNO_3 (aq) \rightarrow Mg(NO_3)_2 (aq) + 2AgCl (g) \) Quick Tip: When balancing chemical equations, always start with balancing atoms that appear only once on both sides, followed by elements that appear in multiple compounds.

(i) Reactant and Product for the reaction:

The reaction is: \[ Zn + H_2SO_4 \rightarrow ZnSO_4 + H_2 \uparrow \]

- Reactants: Zinc (Zn) and Sulfuric acid (\(H_2SO_4\))
- Products: Zinc sulfate (\(ZnSO_4\)) and Hydrogen gas (\(H_2\))



(ii) Thermal dissociation of Ammonium Chloride:

The thermal dissociation of ammonium chloride (\(NH_4Cl\)) occurs when it is heated, and it decomposes into ammonia gas (\(NH_3\)) and hydrogen chloride gas (\(HCl\)).

The reaction is: \[ NH_4Cl \xrightarrow{\Delta} NH_3 + HCl \]

- Substances formed: Ammonia (\(NH_3\)) and Hydrogen chloride (\(HCl\))


Conclusion:

1. In the first reaction, the reactants are zinc and sulfuric acid, and the products are zinc sulfate and hydrogen gas.
2. In the second reaction, ammonium chloride dissociates into ammonia and hydrogen chloride when heated. Quick Tip: Ammonium chloride decomposes into ammonia and hydrogen chloride when heated. This is a common example of a thermal decomposition reaction.

(i) IUPAC Name of the First Compound:

The given compound is an alcohol with 3 carbon atoms and a hydroxyl group (-OH) attached to the terminal carbon atom. The IUPAC name is Propan-2-ol, as the alcohol group is on the second carbon of the chain.



(ii) IUPAC Name of the Second Compound:

The second compound is a carboxylic acid with a 6-carbon chain. The functional group is a hydroxyl group (-OH) at the end of the chain, and it is a hexanoic acid. The IUPAC name is Hexanoic acid.


Conclusion:

1. The IUPAC name for the first compound is Propan-2-ol.

2. The IUPAC name for the second compound is Hexanoic acid.
Quick Tip: The position of functional groups like -OH in alcohols or -COOH in carboxylic acids determines the IUPAC name. Count the carbon atoms in the longest chain, and use the appropriate suffix based on the functional group.

(i) Oxygen:

- Atomic Number: 8

- Valency: 2 (Oxygen can form two bonds, as in water \( H_2O \), where oxygen bonds with two hydrogen atoms).


(ii) Potassium:

- Atomic Number: 19

- Valency: 1 (Potassium has a valency of 1, as it loses one electron to form \( K^+ \) ion, as seen in potassium chloride \( KCl \)).



Conclusion:

1. The atomic number of oxygen is 8, and its valency is 2.

2. The atomic number of potassium is 19, and its valency is 1.
Quick Tip: Oxygen typically has a valency of 2 because it needs 2 electrons to complete its valence shell, while potassium has a valency of 1 because it loses 1 electron to achieve a stable configuration.

(a) Addition and Substitution Reactions:

- Addition Reaction: An addition reaction is a type of chemical reaction in which two or more molecules combine to form a single product. In this reaction, a molecule adds across a double or triple bond in an organic compound. For example, the addition of hydrogen to an alkene in the presence of a catalyst results in an alkane. \[ C_2H_4 + H_2 \xrightarrow{Ni} C_2H_6 \]
- Substitution Reaction: In a substitution reaction, one atom or group of atoms in a molecule is replaced by another atom or group of atoms. A common example of substitution is the halogenation of alkanes. For example, when chlorine reacts with methane, hydrogen is replaced by chlorine: \[ CH_4 + Cl_2 \rightarrow CH_3Cl + HCl \]



(b) Micelle:

A micelle is an aggregate of surfactant molecules in a liquid, such as water, where the hydrophobic (water-repelling) tails of the surfactant molecules are inward and the hydrophilic (water-attracting) heads are on the outside. Micelles are important in the emulsification of oils in water, where they allow the dispersion of non-polar substances in polar solvents. They play a critical role in soap and detergent actions by trapping oil or grease in the center.



(c) Neutralization Reaction:

A neutralization reaction occurs when an acid reacts with a base to form salt and water. The general form of the reaction is: \[ Acid + Base \rightarrow Salt + Water \]
For example, when hydrochloric acid reacts with sodium hydroxide, the result is the formation of sodium chloride and water: \[ HCl + NaOH \rightarrow NaCl + H_2O \]
This reaction is an important process in many biological and chemical systems and is used in titration to determine the concentration of an acid or base.


Conclusion:

1. Addition reactions involve the combination of molecules, while substitution reactions involve the replacement of atoms or groups in a molecule.
2. Micelles are formed by surfactants and are used to emulsify oils in water.
3. A neutralization reaction involves the reaction between an acid and a base to form a salt and water. Quick Tip: In neutralization reactions, the acid and base cancel each other out, resulting in a neutral solution when mixed in the right proportions.

(a) Two Uses of Bleaching Powder:

1. Disinfection: Bleaching powder is used to disinfect drinking water, killing bacteria and other microorganisms. It is commonly used in water treatment plants.

2. Bleaching Agent: It is used in the textile and paper industries as a bleaching agent for clothes and papers.



(b) Corrosion and Methods for its Prevention:

- Corrosion: Corrosion is the gradual destruction of materials, usually metals, by chemical reactions with environmental factors such as air, water, or chemicals. An example of corrosion is the rusting of iron.

- Two Methods to Prevent Corrosion:
1. Galvanization: This is the process of coating the metal (usually iron or steel) with a layer of zinc to prevent rusting. The zinc layer prevents exposure to air and moisture.
2. Oil or Paint Coating: Applying a protective layer of oil, paint, or lacquer prevents direct contact of the metal with water and air, thus preventing corrosion.



(c) One Use of Plaster of Paris:

Plaster of Paris is commonly used in the medical field for making casts for broken bones. It is also used for making molds in art and sculpture.


Conclusion:

1. Bleaching powder is useful in disinfection and bleaching.

2. Corrosion is the degradation of metals, and it can be prevented through methods like galvanization and coating.

3. Plaster of Paris is used in making medical casts and molds. Quick Tip: To prevent corrosion, you can either physically block moisture and air from reaching the metal or use a sacrificial metal like zinc, which corrodes instead of the metal you are trying to protect.

Digestion is the process by which the food we eat is broken down into simpler forms such as sugars, fatty acids, and amino acids. This allows the nutrients to be absorbed into the bloodstream and transported to cells for energy, growth, and repair. The digestive system in humans is a complex series of organs working together to break down food. The process involves both mechanical and chemical digestion.

Process of Digestion in Humans:

1. Ingestion: The process starts when food enters the mouth. The teeth break down the food into smaller pieces (mechanical digestion), and saliva, which contains the enzyme amylase, begins breaking down starch (chemical digestion).

2. Mouth to Stomach: The food is then pushed down the esophagus to the stomach through a process called peristalsis (a wave-like muscle contraction).

3. Stomach: In the stomach, gastric juices containing hydrochloric acid and digestive enzymes break down proteins. The stomach churns food to mix it with digestive juices (mechanical digestion).

4. Small Intestine: The partially digested food moves into the small intestine, where most of the digestion and nutrient absorption occurs. The pancreas secretes enzymes that further break down food, while bile from the liver helps digest fats.

5. Absorption: Nutrients from the digested food are absorbed into the bloodstream through the villi (small finger-like projections) in the small intestine.

6. Large Intestine: Any remaining water and salts are absorbed in the large intestine, and the remaining waste is formed into stool.

7. Elimination: The waste is then excreted through the rectum and anus.


% Diagram of Human Digestive System
\begin{tikzpicture
% Mouth
\node at (1,2) {Mouth;
\draw[thick] (0,2) ellipse (0.5 and 0.3);
% Esophagus
\node at (1,1.4) {Esophagus;
\draw[thick] (0,1.5) -- (0,1);
% Stomach
\node at (1,0.6) {Stomach;
\draw[thick] (0,0) ellipse (1.2 and 0.6);
% Small Intestine
\node at (3,0.5) {Small Intestine;
\draw[thick] (2,0.1) -- (4,0.1);
% Large Intestine
\node at (5,0.5) {Large Intestine;
\draw[thick] (4,0.5) -- (5,0.5);
\draw[thick] (5,0.5) arc[start angle=0,end angle=180,radius=0.4];
% Rectum
\node at (5.5,0.5) {Rectum;
\draw[thick] (5,0.5) -- (6,0.5);
\node at (6,1.0) {Anus;
\draw[thick] (6,0.5) -- (6.5,1);
\end{tikzpicture


Conclusion:

Digestion is a vital process that begins in the mouth and ends with the elimination of waste. The small intestine is where most absorption takes place, while the large intestine focuses on absorbing water. The digestive system works harmoniously to break down food and absorb essential nutrients. Quick Tip: Digestion involves both mechanical processes (e.g., chewing) and chemical processes (e.g., enzymes breaking down food). A balanced diet supports efficient digestion.

Digestion is the process by which the food we eat is broken down into simpler forms such as sugars, fatty acids, and amino acids. This allows the nutrients to be absorbed into the bloodstream and transported to cells for energy, growth, and repair. The digestive system in humans is a complex series of organs working together to break down food. The process involves both mechanical and chemical digestion.

Process of Digestion in Humans:

1. Ingestion: The process starts when food enters the mouth. The teeth break down the food into smaller pieces (mechanical digestion), and saliva, which contains the enzyme amylase, begins breaking down starch (chemical digestion).

2. Mouth to Stomach: The food is then pushed down the esophagus to the stomach through a process called peristalsis (a wave-like muscle contraction).

3. Stomach: In the stomach, gastric juices containing hydrochloric acid and digestive enzymes break down proteins. The stomach churns food to mix it with digestive juices (mechanical digestion).

4. Small Intestine: The partially digested food moves into the small intestine, where most of the digestion and nutrient absorption occurs. The pancreas secretes enzymes that further break down food, while bile from the liver helps digest fats.

5. Absorption: Nutrients from the digested food are absorbed into the bloodstream through the villi (small finger-like projections) in the small intestine.

6. Large Intestine: Any remaining water and salts are absorbed in the large intestine, and the remaining waste is formed into stool.

7. Elimination: The waste is then excreted through the rectum and anus.


% Diagram of Human Digestive System
\begin{tikzpicture
% Mouth
\node at (1,2) {Mouth;
\draw[thick] (0,2) ellipse (0.5 and 0.3);
% Esophagus
\node at (1,1.4) {Esophagus;
\draw[thick] (0,1.5) -- (0,1);
% Stomach
\node at (1,0.6) {Stomach;
\draw[thick] (0,0) ellipse (1.2 and 0.6);
% Small Intestine
\node at (3,0.5) {Small Intestine;
\draw[thick] (2,0.1) -- (4,0.1);
% Large Intestine
\node at (5,0.5) {Large Intestine;
\draw[thick] (4,0.5) -- (5,0.5);
\draw[thick] (5,0.5) arc[start angle=0,end angle=180,radius=0.4];
% Rectum
\node at (5.5,0.5) {Rectum;
\draw[thick] (5,0.5) -- (6,0.5);
\node at (6,1.0) {Anus;
\draw[thick] (6,0.5) -- (6.5,1);
\end{tikzpicture


Conclusion:

Digestion is a vital process that begins in the mouth and ends with the elimination of waste. The small intestine is where most absorption takes place, while the large intestine focuses on absorbing water. The digestive system works harmoniously to break down food and absorb essential nutrients. Quick Tip: Digestion involves both mechanical processes (e.g., chewing) and chemical processes (e.g., enzymes breaking down food). A balanced diet supports efficient digestion.

(a) Fission:

Fission is a form of asexual reproduction in which a single organism divides into two or more separate organisms. It is commonly observed in unicellular organisms such as bacteria and protozoa. The process involves the division of the nucleus and cytoplasm into equal parts, resulting in two or more offspring. There are two types of fission:
1. Binary Fission: A type of fission in which the parent cell divides into two equal parts, producing two genetically identical offspring. Example: Bacteria.
2. Multiple Fission: In this process, the organism divides into many parts simultaneously. Example: Amoeba under adverse conditions.



(b) Regeneration:

Regeneration is the process by which certain organisms can regrow lost or damaged body parts. It is a form of asexual reproduction in some species, although it primarily serves for repair. Organisms capable of regeneration can regrow limbs, tails, or even internal organs. Examples of animals that can regenerate body parts include planarians, starfish, and axolotls. In some cases, the process involves the growth of new cells at the site of injury, which later develop into new tissues or organs.



(c) Budding:

Budding is a form of asexual reproduction in which a new organism develops as a growth or outgrowth (bud) from the parent organism. The bud may eventually detach from the parent, or it may remain attached, forming colonies. This method is commonly seen in organisms like yeast, hydra, and sponges. In hydra, for example, a small bud forms at the side of the parent, eventually breaking free and growing into a new individual.


Conclusion:

1. Fission involves the division of a single organism into two or more parts.
2. Regeneration refers to the ability to regrow lost body parts.
3. Budding is the formation of a new organism from a bud on the parent organism. Quick Tip: Asexual reproduction allows organisms to reproduce rapidly and efficiently without the need for a mate, as seen in processes like fission, regeneration, and budding.

What are Fossils?

Fossils are the remains or traces of organisms that lived in the past, typically preserved in rocks. These can include bones, shells, imprints of leaves, footprints, or even traces of ancient behavior. Fossils are formed when an organism’s remains are buried under layers of sediment, and over time, the remains become mineralized or preserved in other ways.


Role of Fossils as Evidence for Organic Evolution:

Fossils provide crucial evidence for the theory of organic evolution in the following ways:


1. Demonstrating Transitional Forms:

Fossils show intermediate forms between different groups of organisms, providing evidence for gradual evolutionary changes. These transitional fossils demonstrate how one species evolved into another over millions of years. For example, fossils of the Archaeopteryx show characteristics of both reptiles and birds, supporting the idea of the evolution of birds from dinosaurs.


2. Fossil Record Over Time:

Fossils also show the sequential appearance of species over time, which helps trace the gradual changes in organisms. By studying the age and layers of fossils, scientists can create timelines of evolution, showing how life forms have evolved and diversified over millions of years.


3. Supporting Common Ancestry:

Fossils help establish the concept of a common ancestry for various species. Similarities in the fossilized remains of different species indicate that they may have evolved from a common ancestor. This is particularly evident in the fossil record of mammals, where certain skeletal structures are shared among various species.


4. Extinct Species and Evolutionary Dead Ends:

Fossils provide evidence of species that are now extinct, showing how they have evolved over time and eventually disappeared. The extinction of some species also provides insight into environmental changes and survival factors that contributed to the survival or demise of certain organisms.



Conclusion:

Fossils serve as a critical piece of evidence supporting the theory of organic evolution, helping scientists understand the gradual changes in species over time and the process of speciation. Quick Tip: Fossils provide a direct record of life forms from the past, offering a unique glimpse into the history of life and its evolution.

Alternative (Non-Conventional) or Renewable Energy Sources:

Alternative or renewable energy sources refer to energy sources that are naturally replenished over time and are considered sustainable. Unlike conventional sources of energy, such as fossil fuels, renewable energy sources have minimal environmental impact, do not deplete over time, and are considered more environmentally friendly. These sources of energy include solar energy, wind energy, geothermal energy, hydropower, and biomass.

Three Renewable Energy Sources:

1. Solar Energy:

Solar energy is the energy harnessed from the sun. It is the most abundant and widely available renewable source of energy. Solar energy can be captured through solar panels (photovoltaic cells) to produce electricity or through solar thermal systems for heating. It is used for generating electricity, heating water, and powering small devices. The major advantage of solar energy is its sustainability and zero emissions.

2. Wind Energy:

Wind energy is produced by harnessing the kinetic energy of wind through wind turbines. The movement of the blades of the turbine generates mechanical energy, which is converted into electrical energy. Wind farms, both onshore and offshore, are being developed worldwide to produce large amounts of electricity. Wind energy is cost-effective, pollution-free, and renewable, making it an attractive option for energy generation.

3. Biomass Energy:

Biomass energy is derived from organic materials, such as wood, agricultural crops, and animal waste. These materials can be burned or processed to produce heat, electricity, or biofuels (such as ethanol and biodiesel). Biomass is considered renewable because plants and organic materials can be replenished over time. It is a versatile source of energy and can be used for cooking, heating, and generating electricity. Biomass also helps reduce waste in landfills.


Conclusion:

Renewable energy sources, such as solar, wind, and biomass, offer sustainable solutions to meet the growing global energy demand while reducing environmental damage. These sources of energy are essential for reducing our reliance on fossil fuels and mitigating climate change. Quick Tip: Renewable energy sources are sustainable, environmentally friendly, and offer an alternative to fossil fuels. Solar, wind, and biomass are among the most commonly used sources.

The process of transporting water, minerals, and food in plants is crucial for their survival and growth. This process involves various specialized structures, including xylem, phloem, roots, and leaves, working together to move essential substances throughout the plant.

Transportation of Water and Minerals:

1. Root Absorption:

Water and minerals are absorbed from the soil by the roots of the plant. The root hairs increase the surface area for absorption. Water is absorbed through osmosis, and minerals are absorbed through active transport.

2. Xylem Transport:

After absorption, water and dissolved minerals move upward through the plant via the xylem, a tissue specialized for water transport. This movement is driven by capillary action, transpiration (evaporation of water from leaves), and root pressure. Transpiration creates a suction force that pulls water from the roots to the leaves.

3. Transpiration:

Transpiration not only helps in the movement of water and minerals but also cools the plant. It occurs through tiny pores in the leaves called stomata. As water evaporates from the leaves, it creates a negative pressure that pulls more water from the roots through the xylem.

Transportation of Food (Photosynthesis Products):

1. Phloem Transport:

The food produced in the leaves through photosynthesis (mainly glucose) is transported throughout the plant via the phloem. The process of transporting food is called translocation. The movement of food in phloem occurs from areas of high concentration (source, such as leaves) to areas of low concentration (sink, such as roots and fruits). This process is driven by pressure flow mechanism, where high pressure at the source pushes the food into the phloem, and low pressure at the sink facilitates the flow.

2. Storage:

Food can be stored in various plant parts such as roots (e.g., carrots), stems (e.g., potatoes), and fruits (e.g., apples) for later use. These stored nutrients are crucial for the plant's growth during unfavorable conditions.


Conclusion:

The transportation of water, minerals, and food in plants is essential for maintaining the plant's physiological functions. The processes of absorption, transpiration, and translocation ensure that all parts of the plant receive the nutrients required for growth and reproduction. Quick Tip: Transpiration not only aids in the transport of water but also plays a crucial role in cooling the plant. Phloem, on the other hand, is responsible for transporting the food produced in the leaves to other parts of the plant.