The movement of particles in a colloidal system such as an aerosol caused by collision with the molecules in the fluid in which the particles are imbedded is known as Brownian movement.

Since 0^oC = - 273 K, then 666^oC = - 273 + 666 = 393 K

A matter is any substance that has mass and volume. E.g. electron, proton, atom, air, wood etc. Humidity is a general term referring to the water content of a gas and not matter.

The direct transition of a solid to a vapour without passing through a liquid phase is known as sublimation. Examples: the transition of solid CO₂ to CO₂ vapour.

273 K = 0^oC, 75^oC = 273 + 75 = 348 K

273 K = 0^oC 300 K = 300 - 273 = 27^oC

A. The particles of liquid absorb energy from the surrounding to regain the energy lost during evaporation. This absorption of energy from the surroundings makes the surroundings cold. B. Diffusion takes place through the haphazard and random way. C. The process of cooling glass is known as annealing.

Acetone is a solvent and used as a nail polish remover safely.

1. Solid carbon dioxide is commonly called as dry ice.
   1. Nitrous oxide (N₂O) has been used for anesthesia in dentistry and other surgical operations. Solid carbon dioxide is commonly called as dry ice. 3. On heating NH₄Cl, it goes to gaseous state due to the process of sublimation. A change of state directly from solid to gas without changing into liquid state is called sublimation.

Matter has three basic states- solid, liquid and gas. The stationary state does not exist.

P. Nitrous oxide (N₂O) is commonly known as laughing gas. Q. On Kelvin scale, 0^oC is equal to - 273 K. R. Carbon dioxide is used to produce carbonated soft drinks and soda water.

At high temperature and low pressure, a gas approaches to show ideal gas behaviour.

According to the kinetic theory of gases between two successive collisions, a gas molecule in an ideal gas always travels in a straight line path.

Rubidium is a metallic solid.

In a solid, the particles (ions, atoms or molecules) are closely packed together. The forces between particles are strong so that the particles cannot move freely but can only vibrate. As a result, a solid has a stable, definite shape, and a definite volume. Solids can only change their shape by force as when broken or cut.

CFC - Chlorofluorocarbons

273 K = 0^oC,

• 127 ^oC = 273 + (- 127) = 273 – 127 = 146 K.

Benzoyl chloride and propanol are liquid.

Sulphur dioxide gas was used in refrigerator as refrigerant in previous years. Halogenated hydrocarbons are frequently used as refrigerant in refrigerator. Methyl chloride is used in refrigerator as refrigerant. A chlorofluorocarbon (CFC) is an organic compound that contains only carbon, chlorine, and fluorine, produced as a volatile derivative of methane, ethane, and propane. They are also commonly known by the DuPont brand name Freon. The most common representative is dichlorodifluoromethane (R-12 or Freon-12). Many CFCs have been widely used as refrigerants, propellants (in aerosol applications), and solvents.

Calcium chloride is solid in nature.

The water vapour present in air, on coming in contact with the cold glass of water, loses energy and gets converted to liquid state, which we see as water droplets. Hence, A is true and R is the correct explanation of A.

Molecular solids, made up of atoms or molecules are held together by London dispersion forces, dipole-dipole forces, or hydrogen bonds. It is characterised by low melting points and flexibility and are poor conductors. An example of a molecular solid is sucrose.

Liquid state of the matter has no fixed shape, but has a fixed volume. 

Solids have definite shape, distinct boundaries and fixed volumes, i.e. they have negligible compressibility. Solids have a tendency to maintain their shape when subjected to outside force. Solids may break under force, but it is difficult to change their shape; so they are rigid.

Humidity is a term indicating the amount of water vapour present in air. The air around us cannot hold more than a definite amount of water vapour at a given temperature. If the amount of water in air is already high, the rate of evaporation decreases.