CBSE Board Class 10 Science Question Paper 2025 Set 1(31-6-1) Available- Download Solution PDF with Answer Key

In the following experimental setup of electrolysis of water, if P and Q are the gases collected in the test tubes enclosing the electrodes R and S, then select the option/options in which the matching is correct:

(i) P - Oxygen gas, R - Anode

(ii) P - Hydrogen gas, S - Cathode

(iii) Q - Hydrogen gas, R - Cathode

(iv) Q - Oxygen gas, S - Anode

• (A) (i) and (ii)
• (B) (iii) and (iv)
• (C) (i) and (iii)
• (D) (ii) and (iv)

You have three aqueous solutions A, B, and C as given below:

A - Potassium nitrate

B - Ammonium chloride

C - Sodium carbonate


The ascending order of the pH of these solutions is:

• (A) A \(<\) B \(<\) C
• (B) B \(<\) C \(<\) A
• (C) C \(<\) A \(<\) B
• (D) B \(<\) A \(<\) C

Select from the following a statement which is not true about the burning of magnesium ribbon in air:

• (A) It burns with a dazzling white flame.
• (B) A white powder is formed on burning.
• (C) It is an endothermic reaction.
• (D) It is an example of a combination reaction.

A hydrocarbon which does not belong to the same homologous series of carbon compounds is:

• (A) C\textsubscript{4}H\textsubscript{10}
• (B) C\textsubscript{6}H\textsubscript{14}
• (C) C\textsubscript{7}H\textsubscript{14}
• (D) C\textsubscript{10}H\textsubscript{22}

The colour of the solution observed after about 1 hour of placing iron nails in copper sulphate solution is:

• (A) Blue
• (B) Pale green
• (C) Yellow
• (D) Reddish brown

Juice of tamarind turns blue litmus to red. It is because of the presence of a chemical compound called:

• (A) Acetic acid
• (B) Methanoic acid
• (C) Oxalic acid
• (D) Tartaric acid

The water of crystallization is present in:

• (A) Bleaching Powder
• (B) Washing Soda
• (C) Plaster of Paris
• (D) Baking Soda

A tall pea plant with round seeds (TTRR) is crossed with a short pea plant with wrinkled seeds (ttrr). The F\textsubscript{1} generation will be:

• (A) 25% tall with round seeds
• (B) 50% tall with wrinkled seeds
• (C) 75% tall with wrinkled seeds
• (D) 100% tall with round seeds

A pair of endocrine glands located in the human brain is:

• (A) Parathyroid and Pituitary
• (B) Pineal and Thymus
• (C) Hypothalamus and Thymus
• (D) Hypothalamus and Pineal

Select the option having correct matching of the organism given in Column I with the mode of reproduction in Column II:

Column I \hspace{0.2cm Column II



P - Leishmania \hspace{1cm 1. Regeneration

Q - Spirogyra \hspace{1.25cm 2. Multiple Fission

R - Planaria \hspace{1.5cm 3. Binary Fission

S - Plasmodium \hspace{1cm 4. Fragmentation

\textbf - \hspace{4cm 5. Budding

• (A) P-4, Q-2, R-1, S-3
• (B) P-3, Q-4, R-5, S-2
• (C) P-3, Q-4, R-1, S-2
• (D) P-4, Q-3, R-2, S-1

The basic filtration unit of the excretory system in human beings is:

• (A) Nephron
• (B) Urethra
• (C) Neuron
• (D) Urinary bladder

In human alimentary canal, the digestive juice secreted by the gastric glands are:

• (A) Bile, Trypsin, Pepsin
• (B) Hydrochloric acid, Pepsin, Mucus
• (C) Lipase, Bile, Mucus
• (D) Salivary amylase, Pepsin, Bile

Identify from the following the ray diagram which shows the correct path of the reflected ray for the ray incident on a concave mirror as shown:

• (A)
• (B)
• (C)
• (D)

The part of human eye which controls the amount of light entering into it is:

• (A) Iris
• (B) Cornea
• (C) Ciliary muscles
• (D) Pupil

Consider the following food chain:

Grass → Grasshopper → Frog → Snake → Eagle

If the amount of energy available at third trophic level is 50 kJ, the available energy at the producer level was:

• (A) 0.5 kJ
• (B) 5 kJ
• (C) 500 kJ
• (D) 5000 kJ

The incorrect statement about ozone is:

• (A) It is a deadly poisonous gas.
• (B) It shields the surface of the earth from UV radiation from the sun.
• (C) It is used as a refrigerant and in fire extinguishers.
• (D) It is formed by combining oxygen molecules with free oxygen atoms.

Assertion (A): Carbon and its compounds are our major sources of fuels.

Reason (R): Most of the carbon compounds on burning release a large amount of heat and light.

• (A) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
• (B) Both Assertion (A) and Reason (R) are true and Reason (R) is not the correct explanation of Assertion (A).
• (C) Assertion (A) is true, but Reason (R) is false.
• (D) Assertion (A) is false, but Reason (R) is true.

Assertion (A): Xylem tissue moves water and minerals obtained from the soil by the roots.

Reason (R): Xylem tissue is found only in the roots of a plant.

• (A) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
• (B) Both Assertion (A) and Reason (R) are true and Reason (R) is not the correct explanation of Assertion (A).
• (C) Assertion (A) is true, but Reason (R) is false.
• (D) Assertion (A) is false, but Reason (R) is true.

Assertion (A): In the common domestic circuit, the earth wire is connected to a metallic plate buried deep inside the earth.

Reason (R): Earth wire ensures that any leakage of current to the metallic body of the appliance keeps its potential to that of the earth, so the user may not get a severe electric shock.

• (A) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
• (B) Both Assertion (A) and Reason (R) are true and Reason (R) is not the correct explanation of Assertion (A).
• (C) Assertion (A) is true, but Reason (R) is false.
• (D) Assertion (A) is false, but Reason (R) is true.

Assertion (A): Food web is a network of several food chains operating in an ecosystem.

Reason (R): Food web decreases the stability of an ecosystem.

• (A) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
• (B) Both Assertion (A) and Reason (R) are true and Reason (R) is not the correct explanation of Assertion (A).
• (C) Assertion (A) is true, but Reason (R) is false.
• (D) Assertion (A) is false, but Reason (R) is true.

A light green coloured solution of sulphate salt of metal 'P' is taken in a beaker, a rod of another metal 'Q' is put in this solution as shown in the following figures:

(a) How is the brain protected in our body?

A doctor finds in one of his patients that he is not maintaining a proper posture and balance of his body. State the region of brain and also the part of the brain which is responsible for it.

(a) "Proteins control the expression of various characters." Explain this statement by taking an example of "tallness" as a characteristic in plants.

Explain the mechanism of inheritance used by sexually reproducing organisms to ensure the stability of DNA of the species.

Out of the two Media – Medium 1 and Medium 2, in which is the speed of light more?

State reason of bending of the refracted ray away from the normal.

Express refractive index of Medium 2 with respect to Medium 1 in terms of speed of light in two media.

Give reasons:



(i) The sky appears dark to passengers flying at very high altitudes.

We do not clean natural ponds or lakes, whereas an aquarium or a swimming pool needs to be cleaned regularly. Why?

Steam is passed over red hot iron.

Natural gas is burnt in air.

Glucose reacts with oxygen in the cells of our body and provides energy.

As an anti-acid.

As a constituent in making baking powder.

In soda-acid fire extinguishers.

Metal.

Base.

Carbonate.

Name the blood vessel that brings (i) oxygenated blood (ii) deoxygenated blood, to the human heart. Also name that chamber of the heart which receives deoxygenated blood and state how deoxygenated blood from this chamber is sent to the lungs for oxygenation.

List two observations made by Mendel in F\textsubscript{1} generation plants.

Give the (i) percentage of white flowered plants and (ii) ratio of the gene combinations WW, Ww, and ww in F\textsubscript{2} generation.

Write one difference between dominant and recessive trait.

What is the focal length of the convex lens used? Give reason to justify your answer.

Which one of the sets of observations is not correct and why?

Draw a ray diagram to show image formation for any correct set of observations.

Name the defect of vision the person is suffering from.

List two causes of this defect.

Determine the focal length of the lenses used in the spectacles.

Explain the statement "Potential difference between two points is 1 volt".

What do the symbols given below represent in an electric circuit? Write one function of each.

(a) Name an alcohol and a carboxylic acid having two carbon atoms in their structures. Draw their structures and state how this alcohol and carboxylic acid can be converted into a carboxylic acid. What happens when these two compounds react in the presence of an acid? Write chemical equations for the reactions involved in the two cases mentioned above.

What are soaps? Write the structure of a soap molecule. Explain the cleansing action of a soap. Why are soaps not considered suitable for washing clothes in a region where water is hard? How is this problem overcome?

Define Puberty. List any two changes seen in boys at the time of puberty.

Why are testes in human males located outside the abdominal cavity in scrotum?

List any three techniques of contraception used by humans. Which one of these is not meant for males?

Name the part performing the following functions in the human female reproductive system:

(i) Production of eggs

(ii) Site of fertilization

(iii) Site of implantation

(iv) Entry of the sperms

What changes are observed in the uterus:

(i) Subsequent to the implantation of the zygote and

(ii) If an egg does not get fertilized?

(a) What are magnetic field lines? How is the direction of the magnetic field at a point determined? Draw the pattern of magnetic field lines of the magnetic field produced by a current-carrying circular loop. Mark on it the direction of (i) current and (ii) magnetic field lines. Name the two factors on which the magnitude of the magnetic field due to a current-carrying coil depends.

Why can’t two magnetic field lines cross each other? Draw magnetic field lines showing the direction of the magnetic field due to a current-carrying long straight solenoid. State the conclusion which can be drawn from the pattern of magnetic field lines inside the solenoid.

(I) How does electrical conductivity and melting point of a metal change when it is converted to its alloy by mixing a small amount of an element in it?

What are alloys? How is ‘Brass’ (an alloy) prepared?

What is stainless steel? How is it prepared? Write one important property which makes it more useful in making cooking utensils as compared to its primary metal.

Name the movement which causes ‘X’ and ‘Y’ to grow downwards and upwards respectively. (Refer above figure)

Write the name of a hormone that plays a major role in (i) falling of leaves (ii) rapid cell division.

Leaves of the sensitive plant move very quickly in response to ‘touch’. How is this stimulus of touch communicated and explain how the movement takes place?

Name the plant hormone which is synthesized at the shoot tip. How does this hormone help the plant to bend towards light?

Draw a circuit diagram showing the above two resistors X and Y joined in parallel with same battery and same ammeter and voltmeter.

In which combination of resistors will the (i) potential difference across X and Y and (ii) current through X and Y, be the same?

Find the current drawn from the battery by the series combination of the two resistors (X and Y).

Determine the equivalent resistance of the parallel combination of the two resistors (X and Y).