States of Matter

A colloid is a solution in which the particle size ranges between 10^-7 and 10^-5 cm.For example, milk, blood, honey, smoke, ink, gum, starch solution etc.

A true solution is a homogeneous solution in which the solute particles have diameters less than 10^-7cm. i.e., the solute particles are of molecular dimensions. The particles are invisible even under powerful microscopes.For example, sodium chloride in water is a true solution. Most ionic compounds form true solutions in water. Organic compounds like sugar and urea also form true solutions in water.

H₂O is a compound because, 1.The components hydrogen and oxygen cannot be separated by physical methods such as filtration, evaporation. 2.Hydrogen and oxygen are present in a fixed proportion of 1: 8. 3.Energy changes accompany the formation of a compound i.e., heat and light are given out. 4.Properties of water are entirely different from the constituents, hydrogen and oxygen. 5.The boiling point of water is 100^oC at 76 cm Hg i.e., one atmospheric pressure

The property by which certain hydrous crystals lose their water of crystallisation, completely or partially, when exposed to air and crumble into a powder is called efflorescence.for examples Na₂SO₄.10H₂O.Such substances are termed as efflorescent substances.

Atoms in a  molecule are not a type of a mixture.The number of atoms in a molecule is the atomocity of the molecule. 

A mixture of  water and salt is an impure substance since the ratio of combining elements is not fixed.

Sublimation is a direct change from the solid state to gaseous state, without passing through the liquid state. If a mixture contains two solids, one sublimable, and the other non-sublimable, they can be separated by the process of sublimation. The solid that sublimes, escapes in the form of vapours. When these vapours are collected on a cold surface, they condense to form the sublimable solid, known as the sublimate.

This is the correct option as vaccum is not a heterogeneous medium. 

This is the correct option. Oiled paper is a translucent medium. 

In the gaseous state, water molecules have the highest kinetic energy and move rapidly and randomly, far apart from each other.

At standard atmospheric pressure, water exists as a liquid between its freezing point (0 degrees Celsius) and its boiling point (100 degrees Celsius).

Hydrophilic substances are water-loving and dissolve well in water, while hydrophobic substances are water-fearing and do not mix or dissolve well in water. These terms describe the affinity of a substance for water molecules.

This option is correct because when plaster of Paris is heated above 200⁰C, it loses the water molecules and is converted in to anhydrous salts, called dead burnt.

If you live in a place that has lots of snow and ice in the winter, you have probably seen the highway department spreading salt on the road to melt the ice. You may have also used salt on ice when making home-made ice cream. Salt lowers the freezing/melting point of water, so in both cases the idea is to take advantage of the lower melting point. Ice forms when the temperature of water reaches 32 degrees Fahrenheit (0 degrees Celsius). When you add salt, that temperature drops: A 10-percent salt solution freezes at 20؛F (-6؛C), and a 20-percent solution freezes at 2؛F (-16؛C). On a roadway, this means that if you sprinkle salt on the ice, you can melt it. The salt dissolves into the liquid water in the ice and lowers its freezing point.

A substance with a definite shape and definite volume is called solid.