Choose the correct statements from below:

A. Nuclides with same atomic number but different number of neutrons are called Isotopes.
B. Nuclides with same mass number are known as Isotopes.
C. Nuclides with same number of neutrons are called Isobars.
D. More than 99.9% mass of atom is concentrated in nucleus.

Choose the correct answer from the options given below:

A and D Only

The correct answer is Option (3) → A and D Only

A. Isotopes are variants of a chemical element that have number of protons (Atomic number) but different number of neutrons. This means that they have different mass number.

D. Yes, because the nucleus of atom contained both neutrons and protons.