Question

51. The isotopes of an element contain:​

Answer 1

Explanation:

Isotopes of an element contain the same number of protons but different numbers of neutrons. Whereas the former means that isotopically different compounds undergo the same reactions, the latter means that they differ in mass (e.g. 126C and 136C are 12 and 13 atomic mass units, respectively).

Answer 2

Answer:

The same number of protons but different number of neutrons.

Explanation:

Isotopes of an element must have same atomic number (Z) but different mass number A.

Number of protons is equal to the atomic number.

So, isotopes of an element have same number of protons.

Mass number is equal to the sum of number of protons and neutrons i.e. A=p+n

As isotopes of an element have different mass number but same number of protons, thus they must have different number of neutrons.