White light while passing through a glass prism breaks up into light of different colours because

• refractive index of glass for different colours of light is different

• glass prism absorbs white light and emits lights of several colours in different directions

• of total internal reflection of white light on surfaces of the prism

• of the interference of different colours inside the prism

Bats can know about their prey at a distance even in the night by emitting

• infrared lights

• ultraviolet lights

• chemicals from their body

• ultrasonic sounds

A pressure cooker works on the principle of

• elevation of boiling point of water by application of pressure

• making the foodgrains softer by application of pressure

• making the foodgrains softer by application of pressure and temperature

• keeping the foodgrains inside steam for a longer time

A beautiful rainbow on the sky is due to the

• dispersion of sunlight from a water droplet only

• reflection of sunlight from a water droplet only

• reflection and refraction of sunlight from a water droplet only

• refraction, dispersion and reflection of sunlight from a water droplet

From which part of turmeric, is the turmeric powder obtained?

• Dried rhizome

• Dried root

• Dried fruit

• Seed

The ceilings of a concert hall are generally curved

• because they reflect the sound to the audience

• because they can absorb noise

• to have better aeration in the hall

• as any sound from outside cannot pass through a curved ceiling

Which of the following labeled points in the figure given above indicate the unstable state of an object?

• Point A only

• Point B only

• Points A and C

• Points B and D

Rays of light get refracted while passing from air to glass because

• density of glass is higher than that of air

• they cannot be reflected from a glass surface

• glass absorbs energy from the light rays

• speed of light in glass is less than the speed of light in air

The presence of sulphur in gunpowder

• decreases the ignition temperature

• increases the final temperature

• increases explosiveness of the gunpowder

• makes the powder smokeless

Pressure of a gas increase due to increase of its temperature because at higher temperature

• gas molecules repel each other more

• potential energy of the gas molecules is higher

• kinetic energies of the gas molecules are higher

• gas molecules attract each other more