Q1. Medium A is optically denser than Medium B. Which one of the following statements is true?
(a) Speed of light is more in medium A than in medium B
(b) Speed of light is more in medium B than in medium A
(c) Speed of light is same in both A and B
(d) Cannot be compared
Q2. We are not crushed under the weight of atmosphere, because
(a) the pressure inside our body is more than atmospheric pressure.
(b) the pressure inside our body is more than atmospheric pressure and cancels the pressure from outside.
(c) the pressure inside our body is less than atmospheric pressure.
(d) The pressure inside our body is equal to the atmospheric pressure and cancels the pressure from outside.
Q3. A block of iron dropped in a vessel of water sinks to the bottom. This is because
(a) the vessel is not deep enough to allow the block to float.
(b) the weight of the water displaced by the block is less than the weight of the block.
(c) the weight of the block is less than the weight of the water displaced by the block.
(d) The density of water is more than the density of the block.
Q4. Which one of following statements incorrect?
(a) A drum vibrates with a low frequency, and therefore, it produces a low pitched sound.
(b) A whistle has a high frequency, and therefore, it produces a sound of higher pitch.
(c) Generally the voice of a man is shriller than that of a woman.
(d) A bird makes a high pitched sound, whereas a lion makes a low-pitched roar.
Q5. Which of the following process/processes destroy/destroys the magnetic properties of a bar magnet?
Cutting into two pieces
(a) Only I
(b)II and III
(c)I, II, and III
(d)I and IV
Q6. While keeping my ear on railway track,
I. I am able to hear the approaching train sooner through the track than through the air.
II. Sound travels faster through steel as compared to air.
III. Sound travels faster through solids as compared to gases.
Of the above three statements, identify which are observations and which are inferences.
(a) II is an observation, and I and III are inferences.
(b) III is an observation, and I and II are inferences.
(c) I and II are observations, and III is an inference.
(d) I is an observation, and II and III are inferences.
Q7. The common characteristic properties of plastics are:
(a) Durable, good conductor of electricity, and non-reactive
(b) Good conductor of heat, light in weight, and good conductor of electricity
(c) Durable, light in weight, and non-reactive
(d)Durable, good conductor of heat, and non-reactive
Q8. Light is falling on the surface S1, S2 and S3 as shown below:
The surfaces on which the angle of incidence is equal to the angle of reflection are:
(a) S1 and S2
(b) S2 and S3
(c) S1 and S3
(d) All the three surfaces
Q9. IN the diagram of human eye given below, the parts marked by A, B, C and D should be labelled as:
(a) A – ciliary muscle B – pupil, C – lens, and D – cornea
(b) A – iris, B – pupil, C – lens, and D – cornea
(c) A – iris, B – cornea, C – pupil, and D – lens
(d) A – ciliary muscle, B – iris, C – lens, and D – cornea
Q10. Impression of an image persists on the retina of human eye for about:
(a) 1 S
(b) 1/2 S
(c) 1/16 S
(d) 1/25 S
Sol. A medium ‘A’ is said to be optically denser than medium ‘B’, if the speed of light in ‘A’ is lesser than the speed of light in ‘B’ i.e. the refractive index of ‘A’ is greater than the refractive index of ‘B’.
Sol. The reason we, nor other objects, are crushed by the weight of this air is because this external pressure is balanced by our internal pressure
Sol. The weight of the water displaced by the iron block is less than its weight so the iron block sinks.
Sol. Heating and beating destroys the magnetic properties of a bar magnet. If we cut the bar magnet into two parts, then again it will be formed in a magnet. If we seal a magnet then it does not affect its magnet property, it still attracts iron.
Sol. An image stays on the retina for about 1/16 of a second. This feature is called persistence of vision.