Are mass number and atomic number of an element same in all respects ?

The atomic number and the mass number of an element M are 12 and 24 respectively . Calculate the number of neutrons in an atom of the element.

Atomic number and mass number of an element M are 25 and 52 respectively. The number of electrons, protons and neutrons in M^(+2) ion are respectively.

An atom of mass number 15 and atomic number 7 captures an alpha- particle and then emits a proton. The mass number and atomic number of the resulting product will respectively be.

An element X decays , first by positron emission and then two alpha -particles are emitted in successive radiactive decay. If the product nucleus has a mass number 229 and atomic number 89 , the mass number and atomic number of element X are.

(a) What is mean by (i) atomic number, and (ii) mass number, of an element ? Explain with the help of an example (b) What is the relation between the atomic number and mass number of an element ? (c) If an element M has mass number 24 and atomic number 12, how many neutrons does its atom contain ?