An element reacts with oxygen to give a compound with a high melting point. This compound is also soluble in water. The element is likely to be

Write equations for the reactions of

$(i)$ iron with steam

$(ii)$ calcium and potassium with water

Give reasons why copper is used to make hot water tanks and not steel (an alloy of iron).

You are given a hammer, a battery, a bulb, wires and a switch.

$(a)$ How could you use them to distinguish between samples of metals and non-metals ? 

$(b)$ Assess the usefulness of these tests in distinguishing between metals and non-metals.

What type of oxides are formed when non-metals combine with oxygen?

Pratyush took sulphur powder on a spatula and heated it. He collected the gas evolved by inverting a test tube over it, as shown in figure below.

$(a)$ What will be the action of gas on

$(i)$ dry litmus paper ?

$(ii)$ moist litmus paper ?

$(b)$ Write a balanced chemical equation for the reaction taking place.