States of Matter

Kerosene is a hydrocarbon liquid that is less dense than water, which is why it floats on the surface. Petroleum and petrol also have lower densities than water, but kerosene is the standard answer in this context.

Carbon is the basis of all known life on Earth. Its ability to form stable bonds with many other elements allows for the complex molecules required for life.

A gel is a colloid where a liquid is dispersed in a solid medium. Examples include jelly or butter.

All around us are substances that are made of matter. Matter has mass and occupies some space. Different kinds of substances are made up of different matter. Matter can be thus be classified in many ways. Two basic classifications of matter are based on its physical and chemical properties. The physical classification of matter shows its physical appearance that describe the shape, hardness, softness, melting and boiling points. The chemical classification of matter shows the ability of the matter to change its composition to form new substances.

When a solid is in the form of a Lamina, its length and breadth increases on heating. Hence, its area also increases. This is known as the superficial expansion.

Ice has a relative density of 0.92. When ninety-two volumes of water at 4^oC is frozen, it will expand to hundred volumes. Thus, ice is lighter than water and hence it floats on water.

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.