Question

Which one of the following statements is not correct?

(a) Atoms of different elements may have same mass numbers.

(b) Atoms of an elements may have different mass numbers.

(c) All the atoms of an element have same number of protons.

(d) All the atoms of an element will always have same number of neutrons.

Answer 1

(d) All the atoms of an element will always have same number of neutrons.

Two atoms are said to belongs to an element when they have same number of protons. But they can have different number of neutrons. 

e.g. the isotopes of an element have same number of protons but different number of neutrons.