Question

The mass number of a nucleus is

• A. always less than its atomic number
• B. always more than its atomic number
• C. may equal to its atomic number
• D. sometimes less than and sometimes more than its atomic number

Answer 1

The correct option is C may equal to its atomic number

The atoms of different elements have different numbers of protons which is their Atomic number. Meanwhile, the Mass number of an atom equals to the total number of protons + neutrons it contains. Thus, an atom's Mass number can never be smaller than its Atomic number. It is mostly larger than the atomic number and in few cases equal to the atomic number. For example, Hydrogen (H) has both atomic no. and mass no. equal to 1 as it contains one proton and no neutron.

Hence, Option C is the best possible answer.