Question

An element ‘X’ reacts with O₂ to give a compound with a high melting point This compound is also soluble in water. The element ‘X’ is likely to be:

Options

• iron

• calcium

• carbon

• silicon

Answer 1

calcium

Explanation:

Calcium (Ca) combines with oxygen to form Calcium oxide (CaO) with a very high melting point. It dissolves in water to form Calcium hydroxide.

\[\ce{2Ca + O2 -> 2CaO}\]

\[\ce{CaO + H2O -> \underset{(soluble)}{\underset{Calcium hydroxide}{Ca(OH)2}}}\]