Question

The mass number of a nucleus is equal to the number of

• A. neutrons it contains
• B. electrons it contains
• C. nucleons it contains
• D. protons it contains

Answer 1

The correct option is C

nucleons it contains

The explanation for correct option:

(c) nucleons it contains

• nucleus has a mass of A times the mass of a nucleon
• reflects the number of nucleons.
• Protons and neutrons are collectively known as nucleons.
• Hence this option is correct.

The explanation for incorrect options:

(a) neutrons it contains

• A nucleus has a mass of A times the mass of a nucleon
• A reflects the number of nucleons.
• Since in the nucleus there are protons also they are not taken into account.
• Hence this option is not correct.

(b) electrons it contains

• A nucleus has a mass of A times the mass of a nucleon
• A reflects the number of nucleons.
• Since electrons are not present inside the nucleus, they must not be taken into account.
• Hence this option is not correct.

(d) protons it contains

• A nucleus has a mass of A times the mass of a nucleon
• A reflects the number of nucleons.
• Since in the nucleus there are neutrons also they are not taken into account.
• Hence this option is not correct.

Hence the correct option is (c ) nucleons it contains