Question

The sum of protons, electrons and neutrons in the heaviest isotope of hydrogen is:
(A)- 6
(B)- 5
(C)- 4
(D)- 3

Answer 1

Hint: Isotope of any element is that species which have similar atomic number as that parent atom may have but have different atomic mass. They also have similar chemical properties as the parent atom because they have the same no. of protons or atomic number.

Complete answer: Heaviest isotope of hydrogen is tritium which is denoted as ${}_{\text{1}}^{\text{3}}{\text{H}}$, from this it is clear that:
Atomic number of titanium is 1, which is equal to the number of protons because the atomic number of any element is always equal to the no. of protons or no. of electrons present in the neutral atom.
So, from the above point it is also clear that in titanium only 1 electron is present; because titanium is a neutral atom so no. of electrons is equal to no. of protons.
 Atomic mass of titanium is 3, which is the sum of no. of protons and neutrons present in the nucleus. So that only 2 neutrons are present in the nucleus of titanium with 1 proton.
Now, the sum of protons, electrons and neutrons in the titanium is $1 + 1 + 2$ i.e. 4.

The sum of protons, electrons and neutrons in the heaviest isotope of hydrogen i.e. titanium is shown by option (C) i.e. 4.

Note: In this question some of you may do wrong calculation by getting confused in the value or no. of neutrons, because in the simple hydrogen atom neutron is not present. So don’t do calculations by keeping in mind that in titanium which is an isotope of hydrogen, neutrons are not present.