Science Board Question Paper 2025-2026 English Medium Class 10 Question Paper Solution

Observe the figure given below and identify the incorrect step for the activity set-up:

Both plants are kept in the dark room for three days before placing them in separate glass jars.

Both plants are covered with separate wooden bell-jars.

Use vaseline to seal the bottom of the jars with the glass plates.

Both potted plants were kept in sunlight for a few hours before the iodine test for the presence of starch.

Food web

Ecosystem

Ecological pyramid

Food chain

In a synapse, the chemical signal is transmitted from ______.

dendritic end of one neuron to axonal end of another neuron.

axon to cell body of the same neuron.

cell body to axonal end of the same neuron.

axonal end of one neuron to dendritic end of another neuron.

Effect of light.

Effect of gravity.

Rapid cell division in tendril cells in contact with the support.

Rapid cell division in tendril cells that are away from the support.

In accumulation of toxic substances at higher trophic levels of an ecosystem through the food chain, which of the following organisms is affected the most?

Small aquatic plants

Human beings

Small fish

Large fish

In plants, the role of cytokinin is to/in:

promote cell division

wilting of leaves

promote opening of stomatal pore

growth of stem

The number of chromosomes in parents and offspring of a particular species undergoing sexual reproduction remains constant due to ______.

doubling of chromosomes after zygote formation.

halving of chromosomes after zygote formation.

doubling of chromosomes before gamete formation.

halving of chromosomes at the time of gamete formation.

Assertion (A): The basic filtration unit in the kidneys, like in the lungs, is a cluster of very thin-walled blood capillaries. 

Reason (R): Each capillary cluster in the kidney is associated with the cup-shaped end of a coiled tube called Bowman’s capsule.

Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).

Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of Assertion (A).

Assertion (A) is true, but Reason (R) is false.

Assertion (A) is false, but Reason (R) is true.

Assertion (A): Ozone (O₃) gas at higher levels of atmosphere is a product of UV radiation acting on Oxygen (O₂).

Reason (R): The amount of ozone in the atmosphere began to droр sharply in 1980s.

Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).

Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of Assertion (A).

Assertion (A) is true, but Reason (R) is false.

Assertion (A) is false, but Reason (R) is true.

What kind of respiration provides more energy and why?

Separation of right side and left side of the heart is useful to keep oxygenated have different and deoxygenated blood from mixing. Various organisms types of heart.

(I) Fill in the blanks (i) to (iii) correctly according to the type of organisms and their evolution in terms of blood circulation:

(II) Which type of circulation is most efficient?

In the following food chain, 5 J of energy is available to man. Calculate, how much energy was available at the producer level. Why?

Plant → Goat → Man

A blue colour flower (BB) bearing plant is crossed with a plant with white coloured flowers (bb).

1. State the colour of the flowers you would expect in their F₁ progeny.
2. What must be the percentage of white flower plants in the F₂ generation, if the F₁ plants are self-pollinated?
3. State the expected ratio of genotypes BB and bb in F₂ progeny.

In xylem tissue, vessels and tracheids of the roots, stems and leaves are interconnected to form a continuous system of water-conducting channels reaching all parts of the plant. Explain how this is achieved.

Read the following passage and answer the questions that follow:

Attempt either (a) or (b):

1.  
   1. Which process in these plants is minimised to help the plants survive in dry conditions?
   2. Which part of the leaf is responsible for exchange of gases during photosynthesis?
      OR
2. 
   
   1. List the events that occur during the process of photosynthesis.
   2. When are such desert plants likely to take in carbon dioxide from the environment, unlike other plants?
   3. Draw a labelled diagram of stomata with open stomatal pore.

Observe the given diagram and answer the questions that follow:

1. Give the name and type of reproduction shown in the above diagram.
2. Comment on the processes taking place in stage P.
3. Name an organism which reproduces by the above mentioned method.
4. Name the method that can be used to raise plants that have lost their capacity to produce seeds. List any two advantages of growing plants by such a method.

Observe the given diagram and answer the questions that follow:

1. Give the name of the structure and type of reproduction shown in the above diagram.
2. State one advantage and one disadvantage of the above mentioned method of reproduction.
3. Give reason: Asexual reproduction lacks genetic variation.
4. Why have higher organisms resorted to sexual reproduction in spite of its complexity?

When zinc reacts with NaOH, the product formed is ______.

Na₂O

ZnO

Na₂ZnO₂

Zn(OH)₂

In which case/cases will the bulb glow considering that all other connections of electric circuit are complete and working?

Case (i) only

Case (ii) only

Cases (ii) and (iii)

Case (iii) only

The reaction of calcium with cold water is ______.

Less violent, but the heat evolved is sufficient for the hydrogen to catch fire.

Very violent and exothermic and hydrogen catches fire.

Exothermic, but the heat evolved is not sufficient for the hydrogen to catch fire.

Slow and endothermic.

Which of the following compounds will undergo addition reaction?

C₄H₁₀

C₄H₈

C₃H₈

CH₄

In the following equation

\[\ce{x KI + H2O2 -> I2 + y KOH}\]

x and y respectively are:

2, 2

1, 2

2, 1

1, 1

To a small amount of copper oxide in a beaker, when we add dilute hydrochloric acid slowly with stirring, the change in the colour of the solution is due to the formation of ______.

Copper (II) oxide, which is black in colour.

Copper (I) chloride, which is blue in colour.

Copper (II) chloride, which is blue-green in colour.

Copper (I) oxide, which is black in colour.

Which of the following is an example of a displacement reaction?

The combustion of natural gas.

The reaction of a reactive metal with dilute acid.

The electrolysis of water.

The reaction of quick lime with water.

Assertion (A): There are large number of compounds with many carbon atoms linked to each other.

Reason (R): Carbon-Carbon bond is very strong and stable.

Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).

Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of Assertion (A).

Assertion (A) is true, but Reason (R) is false.

Assertion (A) is false, but Reason (R) is true.

Comment on the following property of ionic compounds and give a reason in support of your answer:

Physical nature

Comment on the following property of ionic compounds and give reason in support of your answer:

Melting and boiling points

Give reason:

Potato chips manufacturers fill the packet of chips with nitrogen gas.

Give reason:

Respiration is an exothermic reaction.

Why do we store silver chloride in a dark coloured bottle?

While diluting an acid, why is it recommended that the acid should be added to water and not water to the acid?

Give reason:

Dry HCl gas does not turn blue litmus red whereas dilute hydrochloric acid does.

Give reason:

Blue colour of Copper(II) sulphate crystals turns white on heating.

Write the preparation of the following compound with balanced chemical equation:

NaOH by chlor-alkali process

Write the preparation of the following compound with balanced chemical equation:

Baking Soda

Write the preparation of the following compound with balanced chemical equation:

Plaster of Paris

Read the following passage and answer the questions that follow:

1. Define anode mud.    [1]
2. In electrolytic refining of copper, name the anode and the cathode.    [1]
3. 
   
   1. With the help of chemical equations, show the extraction of copper from its ore Cu₂S.    [2]
      OR
   2. Draw a neat and labelled diagram showing electrolytic refining of copper.    [2]

What is homologous series?

Which two of the following organic compounds belong to the same homologous series?

C₂H₄, C₄H₁₀, C₃H₄, C₄H₆

Write the product(s) in the following reaction:

\[\ce{CH3 - CH2 - OH + CH3COOH ->[Acid]}\]

Write the product(s) in the following reaction:

\[\ce{C2H5OH + O2 ->[Burning]}\]

Why does micelle formation take place when soap is added to water?

Name the following compound:

\[\begin{array}{cc}
\ce{CH3 - C - CH3}\\
||\\
\ce{O}\\
\end{array}\]

Name the following compound:

\[\begin{array}{cc}
\ce{H}\phantom{..............}\\
|\phantom{..............}\\
\ce{H - C - C ≡ C - H}\\
|\phantom{..............}\\
\ce{H}\phantom{..............}\\
\end{array}\]

Name the reaction which is commonly used in the conversion of vegetable oils to fats.

Why is the melting point of C₄H₁₀ higher than C₃H₈?

What happens when a small piece of sodium is dropped in ethanol? Write the equation for this reactions.

Write the products in the following reaction:

\[\ce{CH3COOC2H5 + NaOH ->}\]

Observe the given ray diagram showing refraction through a prism and choose the correct option for colour of rays 1 and 2:

Colour of ray 1 : Blue, Colour of ray 2 : Red

Colour of ray 1 : Green, Colour of ray 2 : Yellow

Colour of ray 1 : Red, Colour of ray 2 : Violet

Colour of ray 1 : Violet, Colour of ray 2 : Red

In an electric circuit carrying current I, a 2 Ω resistor is replaced by an 8 Ω resistor without changing the connected (ideal) battery. Then ______.

current becomes `I/4` and potential difference `V/4`.

current becomes `I/4` and potential difference remains V.

current becomes 4I and potential difference remains V.

current becomes 4I and potential difference `V/4`.

Assertion (A): The needle of a compass, kept in an external magnetic field, always aligns itself in the North-South direction of the Earth. 

Reason (R): The behaviour of the needle of the compass is similar to the behaviour of a freely suspended bar magnet.

Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).

Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of Assertion (A).

Assertion (A) is true, but Reason (R) is false.

Assertion (A) is false, but Reason (R) is true.

What happens when light is scattered from very fine particles of medium? Justify your answer in given case.

What happens when light is scattered from very large size particles of medium? Justify your answer in given case.

With the help of a ray diagram, explain any phenomenon of formation of spectrum in nature.

Redraw the following ray diagram in your answer book and show the path of reflected/refracted ray:

Redraw the following ray diagram in your answer book and show the path of reflected/refracted ray:

Name a device which is used to maintain a constant potential difference in a circuit.

Name a device which is used to change the electric current in an electric circuit.

When the potential difference between the terminals of an electric heater is 110 V, a current of 5 A flows through it. What will be the value of current flowing through it when the potential difference is increased to 220 V?

Consider the given electric circuit:

Calculate the following:

1. Total resistance of the circuit.
2. The electric current drawn from the battery.
3. Potential difference between points P and Q.

Study the given diagram and answer the questions that follow:

1. Write the name of the eye defect shown in the diagram. Where is the image formed in this eye defect with respect to the retina of the eye?
2. List two causes of this eye defect.
3. With the help of a ray diagram, show how this defect of vision is corrected.