The presence of sulphur in gunpowder

• decreases the ignition temperature

• increases the final temperature

• increases explosiveness of the gunpowder

• makes the powder smokeless

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

• Dried rhizome

• Dried root

• Dried fruit

• Seed

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

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

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

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

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

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

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