UP Board Class 10 Science Question Paper 2025 (Code 824 CN) with Answer Key and Solutions PDF is Available to Download

Step 1: Understanding the situation.

For a convex lens, when an object is placed between the focal point (F) and the optical center (O), the image formed is virtual, erect, and diminished. This happens because the rays diverge and appear to come from a point behind the lens.

Step 2: Conclusion.

Thus, the image formed by placing the rod between the focus and the optical center of the lens will be virtual, erect, and diminished.


Final Answer: \[ \boxed{The correct answer is (A) Virtual, erect and diminished.} \] Quick Tip: For convex lenses, when the object is between the focus and the optical center, the image formed is always virtual, erect, and diminished.

Step 1: Formula for the relationship between focal length and radius of curvature.

The relationship between the focal length (f) and the radius of curvature (R) for a concave mirror is given by: \[ f = \frac{R}{2} \]

Step 2: Substituting the given value.

Here, the focal length \( f = 10 \, cm \), so we can solve for \( R \): \[ R = 2f = 2 \times 10 = 20 \, cm \]


Final Answer: \[ \boxed{The correct answer is (A) 20 cm.} \] Quick Tip: The radius of curvature of a concave mirror is twice the focal length. Hence, for a focal length of 10 cm, the radius of curvature is 20 cm.

Step 1: Understanding the angle of deviation.

The angle of deviation \( \delta \) is the angle between the incident ray and the emergent ray after refraction through the prism.

Step 2: Conclusion.

Thus, the correct angle of deviation is \( \delta \), as shown in the figure.


Final Answer: \[ \boxed{The correct answer is (D) \delta.} \] Quick Tip: In a prism, the angle of deviation is measured between the incoming and outgoing rays after refraction.

Step 1: Understanding twinkling of stars.

The twinkling of stars is caused by the refraction of light in the Earth's atmosphere. The light from the stars undergoes multiple refractions as it passes through different layers of the atmosphere, causing the star's brightness to vary.

Step 2: Conclusion.

Thus, the phenomenon of twinkling of stars is due to atmospheric refraction.


Final Answer: \[ \boxed{The correct answer is (A) Atmospheric refraction.} \] Quick Tip: The twinkling of stars occurs because the light from the stars refracts through the Earth's atmosphere at different angles.

Step 1: Understanding the components and their symbols.

- A **voltmeter** is represented by a symbol similar to (iv) in Column-Y.
- A **resistance** is represented by the symbol (ii) in Column-Y.
- A **closed plug key** is represented by the symbol (i) in Column-Y.
- An **electric cell** is represented by the symbol (iii) in Column-Y.

Step 2: Conclusion.

Thus, the correct matching is 1 (iv), 2 (ii), 3 (i), 4 (iii).


Final Answer: \[ \boxed{The correct answer is (A) 1 (iv), 2 (ii), 3 (i), 4 (iii).} \] Quick Tip: Ensure to match the correct electrical component symbol from Column-Y to its name in Column-X.

Step 1: Formula for the resistance of a wire.

The resistance \( R \) of a wire is given by the formula: \[ R = \rho \frac{L}{A} \]
where \( \rho \) is the resistivity, \( L \) is the length of the wire, and \( A \) is the cross-sectional area.

Step 2: Understanding the changes in the second wire.

For the second wire:
- The length is doubled: \( L_2 = 2L_1 \).
- The diameter is halved, so the cross-sectional area becomes \( A_2 = \frac{A_1}{4} \).

Step 3: New resistance calculation.

The new resistance \( R_2 \) will be: \[ R_2 = \rho \frac{2L_1}{A_1/4} = 8 \times R_1 \]
Given \( R_1 = 2 \, \Omega \), we get: \[ R_2 = 8 \times 2 = 16 \, \Omega \]


Final Answer: \[ \boxed{The correct answer is (D) 4 \Omega.} \] Quick Tip: The resistance of a wire increases with its length and decreases with its cross-sectional area.

Step 1: Understanding Fleming’s Left Hand Rule.

Fleming’s left hand rule is used to find the direction of the induced current in a conductor moving through a magnetic field. It states that if you align your left hand so that the thumb, forefinger, and middle finger are mutually perpendicular, then:
- The **thumb** represents the direction of motion of the conductor.
- The **forefinger** represents the direction of the magnetic field.
- The **middle finger** gives the direction of the induced current.

Step 2: Conclusion.

Thus, the correct rule used for the direction of induced current is Fleming’s left hand rule.


Final Answer: \[ \boxed{The correct answer is (B) Fleming’s left hand rule.} \] Quick Tip: Fleming’s left hand rule is for the direction of induced current, while the right hand rule is used for motors and the forces on current-carrying conductors.

Step 1: Understanding IUPAC naming conventions.

The IUPAC name for acetic acid is ethanoic acid. The name "acetic acid" is commonly used in chemistry, but the official IUPAC name is based on the molecular structure, which is derived from ethane.

Step 2: Conclusion.

Thus, the correct IUPAC name for \( CH_3COOH \) is **ethanoic acid**.


Final Answer: \[ \boxed{The correct answer is (B) Ethanoic acid.} \] Quick Tip: The IUPAC name for acetic acid is ethanoic acid, as the molecule is based on ethane with a carboxyl group.

Step 1: Understanding alkenes.

Alkenes are hydrocarbons with at least one carbon-carbon double bond. The correct formula for an alkene is one that has a double bond, such as \( CH_3CH = CH_2 \), which is propene.

Step 2: Conclusion.

Thus, the correct formula for an alkene is \( CH_3CH = CH_2 \).


Final Answer: \[ \boxed{The correct answer is (C) CH_3CH = CH_2.} \] Quick Tip: Alkenes always contain at least one carbon-carbon double bond in their structure.

Step 1: pH Scale Definition.

The pH scale measures the acidity or alkalinity of a solution, with values ranging from 0 to 14. A pH value of 7 is considered neutral, meaning the solution is neither acidic nor alkaline.

Step 2: Conclusion.

Thus, the pH value of a completely neutral solution is 7.


Final Answer: \[ \boxed{The correct answer is (C) 7.} \] Quick Tip: A pH of 7 indicates a neutral solution, such as pure water.

Step 1: Understanding the compound.

The chemical \( Na_2CO_3 \cdot 10H_2O \) is known as washing soda, which is sodium carbonate decahydrate.

Step 2: Conclusion.

Thus, the common name for \( Na_2CO_3 \cdot 10H_2O \) is **washing soda**.


Final Answer: \[ \boxed{The correct answer is (B) Washing soda.} \] Quick Tip: Washing soda is commonly used in laundry detergents and for cleaning purposes.

Step 1: Understanding a combination reaction.

A combination reaction is one where two or more substances combine to form a single product. The burning of carbon in air is a combination reaction because carbon and oxygen combine to form carbon dioxide.

Step 2: Conclusion.

Thus, the correct example of a combination reaction is **burning of carbon in air**.


Final Answer: \[ \boxed{The correct answer is (A) Burning of carbon in air.} \] Quick Tip: In combination reactions, two or more reactants combine to form a single product.

Step 1: Understanding alkali metals.

Alkali metals are the elements in Group 1 of the periodic table, such as lithium (Li), sodium (Na), and potassium (K). Potassium (K) is the only alkali metal in the options.

Step 2: Conclusion.

Thus, the correct alkali metal is **potassium (K)**.


Final Answer: \[ \boxed{The correct answer is (B) K.} \] Quick Tip: Alkali metals are highly reactive and belong to Group 1 of the periodic table.

Step 1: Understanding the Role of Kidneys.

The kidneys are vital organs in the human body, responsible for filtering waste products from the blood and excreting them in the form of urine. This process is a key function in the **excretion** system.

Step 2: Other Functions of the Kidneys.

Although the kidneys are related to other bodily systems like **nutrition** and **respiration**, their primary function is excretion, where they help in maintaining the body's fluid balance and removing waste.

Step 3: Conclusion.

Therefore, the kidneys are primarily associated with **excretion** in the human body.


Final Answer: \[ \boxed{The correct answer is (C) Excretion.} \] Quick Tip: Kidneys are part of the excretory system, and they play a crucial role in removing waste products like urea and excess salts from the body.

Step 1: Brain's Functions Overview.

The brain is the control center of the body and is responsible for a variety of functions:
- **Thinking**: The brain processes information, enables thought, and forms decisions.
- **Regulating the heartbeat**: The brain controls the autonomic nervous system, including regulating the heartbeat through the medulla oblongata.
- **Balancing the body**: The brain, particularly the cerebellum, helps coordinate balance and fine motor control.

Step 2: Conclusion.

Since the brain is involved in all these activities, the correct answer is **all of these**.


Final Answer: \[ \boxed{The correct answer is (D) All of these.} \] Quick Tip: The brain's main role is as the central control system, managing processes ranging from conscious thought to unconscious regulation of vital functions.

Step 1: Understanding Glycolysis.

Glycolysis is the metabolic pathway through which glucose (a six-carbon sugar) is broken down into two molecules of pyruvate (a three-carbon compound). This process occurs in the cytoplasm and does not require oxygen (anaerobic process).

Step 2: Breakdown of Glucose.

During glycolysis, glucose is split into two molecules of **pyruvate** while also producing a small amount of ATP (energy) and NADH.

Step 3: Conclusion.

The final product of glycolysis is **pyruvate**. This pyruvate can then enter the mitochondria for further processing in the citric acid cycle (Krebs cycle) or be converted to lactate in anaerobic conditions.


Final Answer: \[ \boxed{The correct answer is (B) Pyruvate.} \] Quick Tip: Pyruvate is the end product of glycolysis and serves as a key molecule in both aerobic and anaerobic respiration pathways.

Step 1: The Structure of the Stamen.

The stamen is the male reproductive organ of a flower and consists of two main parts:
- **Anther**: The anther is the part that produces pollen, which contains the male gametes (sperm cells).
- **Filament**: The filament is the stalk that supports the anther and holds it in place, allowing for the distribution of pollen.

Step 2: Conclusion.

Since the stamen consists of both the **anther** and the **filament**, the correct answer is **Both (A) and (B)**.


Final Answer: \[ \boxed{The correct answer is (C) Both (A) and (B).} \] Quick Tip: The stamen is the male organ of the flower that produces and releases pollen for fertilization.

Step 1: Mendel’s Early Education.

Gregor Mendel, known as the father of genetics, was born in Austria and received his early education in a **primary school**. He later attended universities for further education, where he studied science and became a monk, conducting his famous experiments with pea plants.

Step 2: Conclusion.

Thus, Mendel received his primary education from a **primary school**.


Final Answer: \[ \boxed{The correct answer is (B) Primary school.} \] Quick Tip: Mendel’s primary education laid the foundation for his groundbreaking work in genetics and inheritance patterns in pea plants.

Step 1: Mendel's Study of Dwarf and Tall Pea Plants.

In Mendel's experiments with pea plants, he studied traits like height, where the tall plant (T) is dominant and the dwarf plant (t) is recessive. According to Mendel's laws of inheritance, the **pure dwarf pea plant** would have the genotype **tt** (homozygous recessive).

Step 2: Conclusion.

Thus, the correct genotype for a pure dwarf pea plant is **tt**.


Final Answer: \[ \boxed{The correct answer is (C) tt.} \] Quick Tip: In Mendelian genetics, recessive traits require two copies of the recessive allele, so a pure dwarf plant must be **tt**.

Step 1: Understanding the Role of Top Carnivores.

A **top carnivore** (or apex predator) is an animal that is at the top of the food chain and has no natural predators. Among the options:
- **Deer**: Herbivores, they feed on plants.
- **Tiger**: A top carnivore that preys on other animals but is not hunted by others.
- **Frog**: Often an amphibian that can eat insects, not a top predator.
- **Snake**: Although some snakes are apex predators, the tiger is considered a top predator in this context.

Step 2: Conclusion.

Thus, the correct answer is the **tiger**, which is a top carnivore in its ecosystem.


Final Answer: \[ \boxed{The correct answer is (B) Tiger.} \] Quick Tip: Top carnivores are at the top of the food chain and are not typically preyed upon by other animals.

Step 1: Understanding Myopia.

Myopia, also known as **near-sightedness**, is a vision defect where distant objects appear blurry, while close objects are clear. This happens because the light rays entering the eye converge in front of the retina.

Step 2: Correction of Myopia.

To correct myopia, a **concave lens** is used. A concave lens diverges light rays before they enter the eye, causing them to focus correctly on the retina.

Step 3: Conclusion.

Thus, the defect of myopia is corrected using a **concave lens**.


Final Answer:
The defect of near-sightedness (myopia) is corrected using a **concave lens**. Quick Tip: A **concave lens** diverges light rays and is used to correct myopia, which occurs when the eye focuses light too early, in front of the retina.

Step 1: Formula for Power of a Lens.

The power \( P \) of a lens is related to its focal length \( f \) by the formula: \[ P = \frac{1}{f} \]
where:
- \( P \) is in dioptres (D),
- \( f \) is in meters (m).

Step 2: Given Values.

We are given that the power \( P = -2 \, D \), so using the formula: \[ f = \frac{1}{P} = \frac{1}{-2} = -0.5 \, m \]
Since the focal length is negative, the lens is a **concave lens**.

Step 3: Conclusion.

Thus, the focal length of the lens is **-0.5 m**, and the nature of the lens is **concave**.


Final Answer:
The focal length of the lens is **-0.5 m**, and the nature of the lens is **concave**. Quick Tip: The **concave lens** always has a negative focal length, which makes the light diverge. It is used to correct myopia (near-sightedness).

Step 1: Refractive Index Formula.

The refractive index \( n \) of a medium is given by the formula: \[ n = \frac{c}{v} \]
where:
- \( c \) is the speed of light in vacuum (\( 3 \times 10^8 \, m/s \)),
- \( v \) is the speed of light in the medium.

Step 2: Given Values.

We are given that the refractive index of diamond \( n = 2.42 \). Using the formula, we can solve for \( v \) (speed of light in diamond): \[ v = \frac{c}{n} = \frac{3 \times 10^8}{2.42} \approx 1.24 \times 10^8 \, m/s \]

Step 3: Conclusion.

Thus, the speed of light in diamond is approximately \( 1.24 \times 10^8 \, m/s \).


Final Answer:
The speed of light in diamond is approximately \( 1.24 \times 10^8 \, m/s \). Quick Tip: The refractive index describes how light bends when entering a different medium. A higher refractive index results in slower speed of light in that medium.

Step 1: Concave Lens Image Formation.

For a concave lens, the image formed is always **virtual**, **erect**, and **diminished**, regardless of the object’s position.

Step 2: Ray Diagram.

For a concave lens, the following ray diagram shows the formation of the image:





Step 3: Explanation of the Diagram.

- The object is placed at a distance greater than the focal point.
- The ray parallel to the principal axis diverges after passing through the lens.
- The ray passing through the focal point diverges and appears to come from the same side of the object.
- The image formed is virtual, upright, and diminished, formed between the lens and the focal point.


Final Answer:
The image formed by a concave lens is **virtual**, **erect**, and **diminished**. Quick Tip: In a concave lens, the image is always virtual, upright, and smaller than the object. The focal length is negative.

Step 1: Understanding the formula.

The work done \( W \) in moving a charge \( Q \) between two points with a potential difference \( V \) is given by the formula: \[ W = Q \times V \]
where:
- \( W \) is the work done (in joules),
- \( Q \) is the charge (in coulombs),
- \( V \) is the potential difference (in volts).

Step 2: Given values.

We are given:
- \( Q = 3 \, C \),
- \( V = 3 \, V \).

Step 3: Calculation.

Now substitute the given values into the formula: \[ W = 3 \times 3 = 9 \, J \]

Step 4: Conclusion.

Thus, the work done in carrying the charge is **9 joules**.


Final Answer:
The work done is \( \boxed{9 \, J} \). Quick Tip: Work done is calculated by multiplying the charge with the potential difference. Remember, the unit of work is joules (J), and charge is in coulombs (C).

Step 1: Formula for Equivalent Resistance in Series.

In a series combination of resistances, the equivalent resistance \( R_{eq} \) is the sum of the individual resistances \( R_1, R_2, R_3, \ldots, R_n \). The formula is: \[ R_{eq} = R_1 + R_2 + R_3 + \ldots + R_n \]
where:
- \( R_1, R_2, R_3, \ldots, R_n \) are the individual resistances in the series.

Step 2: Diagram of Series Combination.

The diagram for the combination of resistances in series is shown below:





Step 3: Explanation.

In a series combination:
- The total current passing through all the resistances is the same.
- The total potential difference is the sum of the potential differences across each resistor.


Final Answer:
The equivalent resistance for resistances in series is \( R_{eq} = R_1 + R_2 + \ldots + R_n \). Quick Tip: In a series circuit, the total resistance is the sum of the individual resistances. The current is the same through all resistors, but the potential difference is divided among them.

Step 1: Diagram of Domestic Electrical Circuit.

The domestic electrical circuit consists of various components like the main switch, fuse, appliances, and power supply connected in a proper arrangement. The schematic diagram is as follows:





Step 2: Explanation.

In this diagram:
- The **main switch** controls the supply of electricity to the entire circuit.
- The **fuse** protects the circuit from overloads or short circuits.
- **Appliances** like bulbs, fans, and other devices are connected in the circuit.
- The **power supply** is typically provided by the mains, either from the utility company or a local generator.


Final Answer:
The labelled diagram for a domestic electrical circuit is shown above. Quick Tip: Always remember that the fuse in a domestic circuit is a safety device that breaks the circuit when there is an overload, preventing damage to appliances.

Step 1: Definition of Electromagnetic Induction.

**Electromagnetic induction** is the process by which a change in magnetic flux through a coil of wire induces an electromotive force (EMF) in the wire. This is the fundamental principle behind electric generators and transformers.

Step 2: How It Happens.

When the magnetic field around a conductor changes (either by moving the conductor or changing the magnetic field), an electric current is induced in the conductor. This current flows if the circuit is closed.

Step 3: Faraday’s Law.

The phenomenon is explained by **Faraday's Law of Induction**, which states that the induced EMF is directly proportional to the rate of change of the magnetic flux through the conductor.


Final Answer:
Electromagnetic induction is the process of generating electric current by changing the magnetic field around a conductor. Quick Tip: Electromagnetic induction is the working principle behind devices like electric generators, transformers, and inductors.

Step 1: Definition of Magnetic Field Lines.

Magnetic field lines are imaginary lines that represent the direction and strength of the magnetic field around a magnetic object. These lines help visualize the magnetic field, showing its path from the north pole to the south pole outside the magnet.

Step 2: Properties of Magnetic Field Lines.

1. **Magnetic field lines never intersect.** They are continuous and form closed loops, going from the north pole to the south pole inside the magnet and from the south pole to the north pole outside the magnet.

2. **The density of the magnetic field lines indicates the strength of the magnetic field.** A greater concentration of field lines means a stronger magnetic field in that area.


Final Answer:
Magnetic field lines are visual representations of the magnetic field.
Two properties are:
1. They never intersect.
2. Their density indicates the strength of the magnetic field. Quick Tip: Magnetic field lines are always directed from the north to the south pole outside the magnet. They help in understanding the direction and strength of the magnetic field.

Step 1: Magnetic Field of a Solenoid.

A **solenoid** is a coil of wire, and when an electric current passes through it, a uniform magnetic field is produced inside the coil. The field outside the solenoid behaves like the field of a bar magnet, with distinct north and south poles.

Step 2: Diagram of Magnetic Field Produced by Solenoid.

Below is the diagram showing the magnetic field produced by a current-carrying solenoid:





Step 3: Explanation of the Diagram.

- The field lines inside the solenoid are parallel and straight, indicating a uniform magnetic field.
- The field outside the solenoid is similar to the field of a bar magnet, with the lines spreading out from the north pole and returning to the south pole.


Final Answer:
The diagram shows the magnetic field produced by a current-carrying solenoid. Quick Tip: The magnetic field inside a solenoid is uniform and parallel, while outside it resembles the field of a bar magnet.

N/A Quick Tip: In oxidation reactions, oxygen is added or hydrogen is removed. In displacement reactions, one element replaces another in a compound.

N/A Quick Tip: The activity series helps predict reactivity in displacement reactions, and the IUPAC nomenclature ensures systematic naming of aldehydes and ketones.

N/A Quick Tip: Carbon’s versatility stems from its ability to form a variety of bonds, while corrosion can be controlled through methods like galvanization and painting.

N/A Quick Tip: Homologous series compounds share similar chemical properties, while micelles are important in cleaning and detergent action. Metals and non-metals have distinct physical and chemical properties.

N/A Quick Tip: Non-biodegradable materials pose serious environmental risks, and recycling or reusing such materials helps reduce pollution.

N/A Quick Tip: Understanding trophic levels helps study energy transfer in ecosystems and the interdependence of organisms.

N/A Quick Tip: Proper waste management techniques like segregation and recycling reduce environmental pollution and conserve resources for future generations.

N/A Quick Tip: Bryophyllum exhibits a unique form of vegetative reproduction, making it an excellent example of a plant capable of producing offspring without seeds.

N/A Quick Tip: Spore formation is an efficient way for plants to reproduce in environments where seeds cannot be produced, like in some moist and shaded habitats.

N/A Quick Tip: Seeds are vital for plant reproduction and dispersal. They enable plants to survive in different environmental conditions and ensure the continuation of plant species.

N/A Quick Tip: Lymph plays a key role in the body’s defense system and in maintaining fluid balance between tissues and blood.

N/A Quick Tip: Plants exhibit complex responses to external stimuli that help them adapt to their environment, ensuring optimal growth and survival.

N/A Quick Tip: Reflex actions are fast, automatic responses to stimuli that do not involve the brain, helping protect the body from injury.