Matter in Our Surrounding Test - 8

The temperature above which a gas cannot be liquefied is known as critical temperature. Critical temperature can be changed by changing pressure of the gas.

Out of the given sets of substances, salt, sugar and chalk are solids under ordinary temperature. Mercury, water, oxygen and nitrogen are not solids. Mercury and water are liquid at room temperature. Oxygen and nitrogen are gases.

(1) Solid Element - Gold occurs in solid state.
(2) Compounds - Sugar(Cane sugar - C₁₂H₂₂O₁₁)is made of two or more elements (C, H and O) which are chemically combined in a fixed proportion by mass.
(3) Mixture - Salt solution consists of two or more compounds (Sodium chloride,and Water)which are not chemically combined.
(4) Liquid element - Mercury is an element which is a liquid at room temperature.

(1) Solids have the least inter-particle space among all the states of matter. The intermolecular forces of attraction are stronger in solids as compared to other state of matter.
(2) Gases have the maximum intermolecular space between them because their particles are loosely packed and their positions are not fixed so they also have maximum kinetic energy as they can move in all directions.
(3) Liquids are the state of matter which do not have fixed shape but have fixed volume.
(4) A mixture contains more than one substance (element and/or compound) mixed in any proportion. A mixture has a variable composition.

In solids, the intermolecular forces are very strong, and the constituent particles are closely packed. In solid state the constituent particles are arranged in a closely packed.  Solids are the state of matter which have definite shape, distinct boundaries and fixed volume.
So, all statement are correct for solid state.

An almirah is solid because its material is hard and rigid, has fixed shape and volume, and has a very high density. The almirah may break under force but it is difficult to change its shape (rigidity). All these properties - a definite shape (rigidity), distinct boundaries, and fixed volumes (negligible compressibility) - are possessed by solid substances only.

Particles of solids ( sugar) have the very high force of attraction, particles of liquid (water) have less force of attraction than solids and particles of gases ( oxygen) have very less force of attraction. So correct order of increasing attraction between particles is Oxygen, water and sugar.

Solids substances have the strongest inter-particle force of attraction. In the given substances, sodium bromide is solid, ethyl alcohol is liquid and ammonia and carbon dioxide are gases. So, the particles of Sodium bromide have the strongest force of attraction.

When the pressure increases on the particles of gas then that these particles come together and their intermolecular attraction force increases due to which they get converted into liquid form.

The temperature at which a solid melts to become a liquid at the atmospheric pressure is called its melting point. The process of melting, that is, change of solid state into liquid state is also known as fusion. A substance is said to be in a liquid state if under normal pressure its melting point is below the room temperature. Melting point of a solid and the freezing point of a liquid are same.
Melting point and freezing point describe the same transition of matter from liquid to solid (freezing) or equivalently, from solid to liquid (melting). while ice is freezing or melting, its temperature is not changing. It is stuck on 0°C during the entire melting or freezing process. That is, when matter is transitioning from solid to liquid (melting) or liquid to solid (freezing), its temperature is fixed at the melting/freezing point, which is the same temperature.
So, statement A and B are correct .