Chemical reactions

In the thermal decomposition reactions, the compound decomposes by heat into its .....................

• simple components

• primary elements

• other compounds

• all the previous answers

When we heat mercuric oxide, we get ................

• mercuric oxide and water

• mercuric oxide and oxygen

• mercury and hydrogen

• mercury and oxygen

When copper hydroxide is heated, we obtain ................

• copper carbonate and water

• copper oxide and water

• copper and hydrogen

• copper oxide and hydrogen.

When calcium carbonate is heated, ...............................are obtained.

• calcium bicarbonate and carbon dioxide

• calcium hydroxide and carbon dioxide

• calcium oxide and carbon monoxide

• calcium oxide and carbon dioxide

On heating copper carbonate, the colour changes from .................

• blue to black

• green to black

• black to green

• green to blue.

Most metal sulphates decompose when they are heated to metal oxide and ................... gas.

• CO₂

• O₂

• SO₂

• SO₃

On heating copper sulphate, a ...................... colour is formed.

• black

• green

• blue

• red

Copper sulphate is decomposed by heat into ...................

• black copper oxide only

• sulphur trioxide gas only

• sulphur dioxide gas and black copper oxide

• black copper oxide and sulphur trioxide gas.