NCERT Question 3 (MCQ) - Chapter 3 Class 10 - Metals and Non-Metals

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.

Answer:-

It is given that the element reacts with oxygen to give a high melting point .

• Hence, the element must be very reactive and must form an ionic bond .
• Ionic bonds are are formed between electropositive metals and electronegative non-metals
• Carbon and Silicon are neither electropositive nor electronegative. They form covalent bonds . 

• So, the element can either be Calcium or Fe 

It's also given that the compound is soluble in water.

• The metal must be an alkali metal.
• From the given options, only Calcium is an alkali metal.

Therefore, the element is most likely to be Calcium (Ca) .

So, the correct answer is (a)