Question : A balloon filled with helium rises in the air because

Option 1: air exerts an upward force on the balloon.

Option 2: the balloon is weightless.

Option 3: helium is less denser than air.

Option 4: helium pushes down on the air below the balloon.

Question : A tax is said to be regressive when its burden falls on

Option 1: Less heavily on the poor than on the rich.

Option 2: More heavily on the poor than on the rich.

Option 3: Equally on the poor as on the rich.

Option 4: None of these

Question : If the radius of a hemispherical balloon increases from 4 cm to 7 cm as air is pumped into it, find the ratio of the surface area of the new balloon to its original.

Option 1: 16 : 21

Option 2: 49 : 16

Option 3: 20 : 49

Option 4: 21 : 12

Question : Which among the following is responsible for the rotation of the plane of oscillation of Foucault's pendulum?

Option 1: Centripetal force

Option 2: Viscous drag of air

Option 3: Centrifugal force

Option 4: Coriolis force

Question : The measure of the force that can cause an object to rotate about an axis is called:

Option 1: moment of inertia

Option 2: power

Option 3: torque

Option 4: centripetal force

Question : Carbon monoxide is an inflammable gas. Which one of the following is also inflammable?

Option 1: Helium

Option 2: Nitrogen

Option 3: Oxygen

Option 4: Hydrogen