Question

An element reacts with oxygen to give a compound with a high melting point.The element is likely to be

(A) Calcium

(B) Silicon

(C) Carbon

(D) Iron

Answer 1

When carbon reacts with oxygen it forms carbon dioxide. this carbon dioxide is a gas. gases do not possess melting point. so option C is not correct
Silicon reacts with oxygen and forms silicon dioxide. This is insoluble in water. so option B is not correct
Iron reacts with oxygen and forms Iron dioxide. This is insoluble in water. so option D is not correct
Calcium reacts with oxygen and forms calcium oxide. This calcium oxide dissolves in water and forms calcium hydroxide.
The melting point of calcium oxide is nearly 2,5000C.
So the answer is A