English Medium Class 10 - CBSE Question Bank Solutions for Science

A student obtained a sharp image of a burning candle, placed at the farther end of a laboratory table, on a screen using a concave mirror. For getting better value of focal length of the mirror, the subject teacher suggested him for focusing a well illuminated distant object. What should the student do?

(A) He should move the mirror away from the screen.

(B) He should move the mirror slightly towards the screen.

(C) He should move the mirror as well as the screen towards the newly selected object.

(D) He should move only the screen towards the newly selected object.

A student cannot see a chart hanging on a wall placed at a distance of 3 m from him. Name the defect of vision he is suffering from. How can it be corrected? Draw ray diagrams for the (i) defect of vision and also (ii) for its correction.

State one role of ciliary muscles in the human eye.

State the types of mirrors used for (i) headlights and (ii) rear view mirror, in cars and motorcycles. Give to justify your answer in each case.

An old man cannot see objects closer than 1 m from the eye clearly. Name the defect of vision he is suffering from. How can it be corrected? Draw ray diagram for the (i) defect of vision and also (ii) for its correction.

What eye defect is hypermetropia? Describe with a ray diagram how this defect of vision can be corrected by using an appropriate lens.

What is Hypermetropia (far sightedness)? 

Draw a ray diagram to show how Hypermetropia is defect can be corrected using a lens.

List two causes of presbyopia. Draw labelled diagram of a lens used for the correction of this defect of vision. 

When do we consider a student sitting in the class to be myopic? List two causes of this defect. Explain using a ray diagram how this defect of eye can be corrected.

The near point of the eye of a person is 50 cm. Find the nature and power of the corrective lens required by the person to enable him to see clearly the objects placed at 25 cm from the eye?

The near point of the eye of a person is 50 cm. Find the nature and power of the corrective lens required by the person to enable him to see clearly the objects placed at 25 cm from the eye?

Draw a ray diagram to show the formation of the image, when the object is placed between optical centre and principal focus of a convex lens.

State the signs and values of magnifications in the above mentioned case.

Answer the following question.
Write the modification in the curvature of the eye lens which enables us to see the nearby objects clearly?

A person is unable to see objects distinctly placed within 50 cm from his eyes.

(a) Name the defect of vision the person is suffering from and list its two possible causes.

(b) Draw a ray diagram to show the defect in the above case.

(c) Mention the type of lens used by him for the correction of the defect and calculate its power. Assume that the near point for the normal eye is 25 cm.

(d) Draw a labeled diagram for the correction of the defect in the above case.

A teacher gave two test tubes to the students, one containing water and the other containing sodium hydroxide. She asked them to identify the test tube containing sodium hydroxide solution. Which one of the following can be used for identification?

Which of the following is true for an unbalanced chemical equation?

Which of the following is Not True with respect to the neutralisation reaction?

Before burning in air, the magnesium ribbon is cleaned by rubbing with sand paper to: