Class 9 chemistry chapter 1

In which of the following conditions the distance between molecules of hydrogen gas would increase?

(I) Increasing pressure on hydrogen contained in a closed container.

(II) Some hydrogen gas leaking out of the container.

(III) Increasing the volume of the container of hydrogen gas.

(IV) Adding more hydrogen gas to the container.

• (I), (III)

• (I), (IV)

• (II), (III)

• (II), (IV)

When a gas jar full of air is placed upside down on a gas jar full of Bromine vapours, the vapours of bromine from the lower jar go to the upward jar. According to this experiment :

• Air is heavier than bromine

• Both have the same density

• Bromine is heavier than air

• Bromine can't be heavier than air because it is going against the gravity.

A form of matter has not a fixed shape, but has a fixed volume. One example of this type of matter is :

• Krypton

• Kerosene

• Carbon dioxide

• Carbon steel

Which of the following statements is not true ?

• The molecules in a solid vibrate about a fixed position.

• The molecules in a liquid are arranged in a regular pattern.

• The molecules in a gas exert negligibly small forces on each other.

• The molecules of a gas occupy all the space available.

When water at 0 degrees Celsius freezes form ice in the same temperature, then it :

• Absorbs some heat

• Releases some heat

• Neither absorbs nor releases

• Absorbs exactly 3.34 x 10^5 J/kg of heat