Class 10 ScienceImportant Questions for Board Exams

Write a balanced chemical equation with state symbols for: (a) Burning of magnesium ribbon in air (b) Decomposition of ferrous sulphate crystals.

Why does the colour of copper sulphate solution change when an iron nail is dipped in it?

What is a redox reaction? Give one example.

Define corrosion. How can it be prevented?

Why does tooth decay start when the pH of the mouth falls below 5.5?

What is a neutralisation reaction? Give one example from daily life.

How is baking soda different from washing soda? Give chemical formulae and one use of each.

What happens when a metal carbonate reacts with acid? Write equation for marble and hydrochloric acid.

Write the steps involved in the extraction of a highly reactive metal like aluminium from its ore.

What is the thermite reaction? State its one industrial application.

Why are ionic compounds good conductors of electricity in solution but not in solid state?

How does the reactivity series help in explaining the displacement reactions?

What is a homologous series? Give two characteristics and the first three members of the alkane series.

Explain the cleansing action of soaps. Why do soaps not work well in hard water?

Write the structural formula of ethanoic acid. What happens when sodium hydrogen carbonate is added to it?

What is saponification? Write the equation.

Draw a well-labelled diagram of the human heart and describe how blood is pumped through the body.

Explain the process of photosynthesis. What is the significance of stomata?

What is the role of kidneys in human beings? Explain with the help of a labelled diagram.

How is aerobic respiration different from anaerobic respiration?

Draw a labelled diagram of a neuron. Explain how nerve impulse travels across a synapse.

What is a reflex action? Give one example and draw the reflex arc.

Compare the nervous and hormonal systems of coordination.

What is phototropism? Explain with a labelled diagram.

Draw a diagram of the human male reproductive system and label any four parts.

Distinguish between sexual and asexual reproduction. Give two advantages of sexual reproduction.

What are the different methods of contraception?

Explain vegetative propagation with two examples.

What are Mendel's laws of inheritance? Explain the law of segregation with a monohybrid cross.

In humans, sex is determined by sex chromosomes. Explain how.

How does the creation of variations in a species promote survival?

A tall pea plant (TT) is crossed with a short pea plant (tt). What would be the phenotypic ratio in the F2 generation?

An object 5 cm in length is placed 25 cm in front of a concave mirror of focal length 10 cm. Find the position, size and nature of the image.

Explain with a ray diagram how a convex lens forms a real and inverted image when the object is beyond 2F.

The refractive index of glass is 1.5. What is the speed of light in glass?

A concave lens has a focal length of 15 cm. At what distance should an object be placed so that it forms an image at 10 cm from the lens?

Draw a labelled diagram of the human eye. Explain how it adjusts its focal length to see objects at different distances.

A person cannot see objects closer than 1 m. What is his defect and how can it be corrected?

Explain why the sky appears blue during the day and the sun appears red at sunrise/sunset.

What is the Tyndall effect? Give one example from nature.

Draw a circuit diagram for three resistors connected in parallel. Derive the equivalent resistance.

An electric bulb is rated 220V and 100W. When it is operated at 110V, what power will it consume?

Why are copper and aluminium wires generally used for electricity transmission?

How much heat will be generated by a 40W electric heater in 1 hour?

Draw a labelled diagram of an AC generator and explain how it works.

State Fleming's left hand rule. Give one application.

What is electromagnetic induction? State Faraday's law.

Why is it important to have earthing in domestic electrical circuits?

What is biological magnification? Why does it occur at higher trophic levels?

How does ozone layer depletion occur? What are its harmful effects?

Construct a food chain with four trophic levels using organisms of a grassland ecosystem.

Why is the flow of energy in an ecosystem unidirectional?