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 (a) Calcium (b) Carbon (c) Silicon (d) Iron

Solution: Correct answer is option (a) Calcium.

Calcium reacts with oxygen to give calcium oxide. Calcium oxide is soluble in water to give Calcium Hydroxide.

Carbon forms carbon-oxide with oxygen which is gas, hence option B is wrong

Silicon reacts with oxygen and forms silicon dioxide. This is insoluble in water. So option C is not correct.

Iron reacts with oxygen and forms Iron dioxide. This is insoluble in water. So option D is not correct.