Test: Effect Of Heat And Pressure On Matter - Class 9 MCQ

Rise in temperature gives the particles some energy to move faster.

Latent heat of fusion is the amount of heat energy required to change 1 kg of solid into liquid state without any change in temperature, at its melting point.

Liquids will flow and fill up any shape of container. Solids like to hold their shape. In the same way that a large solid holds its shape, the atoms inside of a solid are not allowed to move around too much. Atoms and molecules in liquids and gases are bouncing and floating around, free to move where they want.

Carbon dioxide is a gas and has a weak intermolecular force of attraction between its molecules. It can be easily solidified and even liquified because it has a low melting point and low boiling point.

Naphthalene undergoes sublimation easily i.e., the change of state of naphthalene from solid to gas without the intervention of the liquid state. Thus, naphthalene balls keep on forming naphthalene vapours which disappear into the air with time without leaving any solid.

At 50°C water will be in its liquid state.

LPG (liquefied petroleum gas) is a fuel that is made up of petroleum gas. On compressing this petroleum gas it forms liquid.

Increases in heat energy can break attractions between particles and trigger a change of state.

For example, when water freezes water molecules are held in a crystalline structure by hydrogen bonds that form between neighboring water molecules. As heat is added to ice, some of the hydrogen bonds will be broken. This will allow more and more water molecules to move freely and the ice will melt and transition into the liquid state.

Water vapours at 100 degree Celsius has more energy than liquid water at 100 degree Celsius. This is due to the fact that on converting liquid into gas, latent heat of vaporisation is required. Thus the total energy of steam is the sum of latent heat and kinetic energy whereas liquid water consists of only kinetic energy.
Hence, we can say that molecules of steam have higher energy than the molecules of liquid water.

The kinetic theory of matter can be used to explain how solids, liquids and gases are interchangeable as a result of increase or decrease in heat energy. When an object is heated the motion of the particles increases as the particles become more energetic.

Kinetic Molecular Theory states that gas particles are in constant motion and exhibit perfectly elastic collisions. Kinetic Molecular Theory can be used to explain both Charles' and Boyle's Laws. The average kinetic energy of a collection of gas particles is directly proportional to absolute temperature only.

The temperature below the freezing point the atoms are pressurised and get attached to one another closely which provide them a fixed volume and shape that is solid.

If we will take the example of ice, a solid so when melting or fusion takes place ice converts to water a liquid.

The color of plasma is determined by the photons, which are emitted when the electrons recombine with the ions (or when excited electrons relax into a lower energy state).

It is because boiling point is a particular temp. at which a liquid starts changing into gas at the atmospheric pressure.