Class 9 Science Chapter 2 MCQ

Here, all these statements are correct. Hence your answer will be option [D].

Decaying of wood and burning of wood are chemical changes, because in this processes, the chemical composition of wood is changed and the new substance are formed, which cannot be converted back into their original form. In Sawing of wood and hammering of a nail into a piece of wood, chemical composition of wood is not changed, therefore, option [C] is physical change. Actually, rusting of an article, made up of iron is called corrosion. Corrosion is a chemical change because rust is a chemical compound (hydrated iron oxide) which is totally different from element iron (Fe).

Ice and air are homogeneous in nature as their particles are not distinctly visible. A homogeneous mixture has a uniform composition throughout its mass. It has no visible boundaries of separation between its various constituents. Example – air, sugar solution, brass etc. A heterogeneous mixture does not have a uniform composition throughout its mass. It has visible boundaries of separation between its various constituents. Example – soil, wood, blood etc.

Milk is considered to be an impure substance as it is an emulsion. Emulsion is a colloid in which minute droplets of one liquid are dispersed in another liquid, which is not miscible with it.

The substance which is dissolved in a liquid to make a solution is called solute and the liquid in which solute is dissolved is known as solvent. For example, salt solution is made by dissolving salt in water, so in salt solution “salt” is the solute and water is the “solvent”.

Here, are all the statements are correct. Hence, your answer will be option [D].

Here, are all the statements are correct. Hence, your answer will be option [D].

Here, are all the statements are correct. Hence, your answer will be option [D].

Here, are all the statements are correct. Hence, your answer will be option [D].

i) If the substance does not have a fixed melting point, boiling point, etc., it is a mixture. ii) If the substance has a fixed melting point, boiling point, etc., it is considered as a compound.