English Medium कक्षा १० - CBSE Question Bank Solutions for Science

How is Joule's law effect useful in electric circuits where fuse is used as a safety device?

Write the balanced equation for the following chemical reaction.

\[\ce{Hydrogen + Chlorine -> Hydrogen chloride}\]

Write the balanced equation for the following chemical reaction.

\[\ce{Barium chloride + Aluminium sulphate -> Barium sulphate + Aluminium chloride}\]

Write the balanced equation for the following chemical reaction.

\[\ce{Sodium + Water -> Sodium hydroxide + Hydrogen}\]

Write the importance of ciliary muscles in the human eye. Name the defect of vision that arises due to gradual weakening of the ciliary muscles. What types of lenses are required by the person suffering from this defect to see the objects clearly?

Akshay, sitting in the last row in his class, could not see clearly the words write on the blackboard. When the teacher noticed it, he announced if any student sitting in the front row could volunteer to exchange his seat with Akshay. Salman immediately agreed to exchange his seat with Akshay. He could now see the words written on the blackboard clearly. The teacher thought it fit to send the message to Akshay’s parents advising them to get his eyesight checked.

In the context of the above event, answer the following questions:-

(a) Which defect of vision is Akshay suffering from? Which type of lens is used to correct this defect?

(b) State the values displayed by the teacher and Salman.

(c) In your opinion, in what way can Akshay express his gratitude towards the teacher and Salman?

Do you know that the corneal-impairment can be cured by replacing the defective cornea with the cornea of the donated eye? How and why should we organise groups to motivate the community members to donate their eyes after death?

Millions of people in the developing countries of the world are suffering from corneal blindness. These persons can be cured by replacing the defective cornea with the cornea of a donated eye. A charitable society of your city has organised a campaign in your neighbourhood in order to create awareness about this fact. If you are asked to participate in this mission, how would you contribute in this noble cause?

(i) State the objective of organising such campaigns.

(ii) List two arguments which you would give to motivate the people to donate their eyes after death.

(iii) List two values which are developed in the persons who actively participate and contribute in such programmes.

A student is unable to see clearly the words written on the blackboard placed at a distance of approximately 4 m from him. Name the defect of vision the boy is suffering from. Explain the method of correcting this defect.

Draw ray diagram for the:-

(i) defect of vision and also

(ii) for its correction.

List three common refractive defects of vision. Suggest the way of correcting these defects.

About 45 lac people in the developing countries are suffering from corneal blindness. About 30 lac children below the age of 12 years suffering from this defect can be cured by replacing the defective cornea with the cornea of a donated eye. How and why can students of your age involve themselves to create awareness about this fact among people?

Why is the amount of gas collected in one of the test tubes in the following Activity double of the amount collected in the other? Name this gas.

• Take a plastic mug. Drill two holes at its base and fit rubber stoppers in these holes. Insert carbon electrodes in these rubber stoppers as shown in the following Fig.
• Connect these electrodes to a 6 volt battery.
• Fill the mug with water such that the electrodes are immersed. Add a few drops of dilute sulphuric acid to the water.
• Take two test tubes filled with water and invert them over the two carbon electrodes.
• Switch on the current and leave the apparatus undisturbed for some time.
• You will observe the formation of bubbles at both the electrodes. These bubbles displace water in the test tubes.
• Is the volume of the gas collected the same in both the test tubes?
  • Once the test tubes are filled with the respective gases, remove them carefully.
• Test these gases one by one by bringing a burning candle close to the mouth of the test tubes.

Caution: This step must be performed carefully by the teacher.

• What happens in each case?
• Which gas is present in each test tube?

Write the balanced chemical equation for the following and identify the type of reaction.

\[\ce{Zinc carbonate(s) -> Zinc oxide(s) + Carbon dioxide(g)}\]

What does one mean by exothermic reaction? Give example.

Why are decomposition reactions called the opposite of combination reactions? Write equations for these reactions.

Write one equation for decomposition reactions where energy is supplied in the form of heat.

A person with a myopic eye cannot see objects beyond 1.2 m distinctly. What should be the type of the corrective lens used to restore proper vision?

What is the far point and near point of the human eye with normal vision?

The far point of a myopic person is 80 cm in front of the eye. What is the nature and power of the lens required to correct the problem?

Will current flow more easily through a thick wire or a thin wire of the same material, when connected to the same source? Why?

Let the resistance of an electrical component remains constant while the potential difference across the two ends of the component decreases to half of its former value. What change will occur in the current through it?