A matter is anything that has mass, occupies space and can be perceived by our senses. For example, the water we drink and the clothes we wear are the matters.

Give reason: When magnesium is burnt in the air, there is an increase in mass after the reaction.

When magnesium is burnt in the air, the oxygen from the air reacts with magnesium to form a product magnesium oxide. Thus, the mass of utilised oxygen also gets added to the mass of magnesium used for burning. The reaction is as follows: 2 Mg + O 2 → 2 MgO

Give two examples for the following: The substances which sublime.

Sublimation is the process in which solid turns directly into gas without converting into liquid. The substances undergoing sublimation are termed as sublimates. Solid → heat Gas Two examples of sublime substances are ammonium chloride and dry ice.