Question

The \[\dfrac{{\text{n}}}{{\text{p}}}\] ratio for \[_{\text{1}}{{\text{H}}^{\text{1}}}\] is:
(A) 1
(B) 2
(C) 3
(D) zero

Answer 1

Hint: The number of protons is equal to the atomic number Z. The number of neutrons is equal to the difference between the mass number A and the atomic number Z.

Complete step by step answer:
An element is represented by the chemical symbol \[_{\text{Z}}{{\text{X}}^{\text{A}}}\] . Here X is the chemical symbol of the element, A is the atomic number of the element and Z is the mass number of the element. The atomic number is written as the subscript and the mass number is written as superscript. Atomic number is equal to the number of protons. It is also equal to the number of electrons in a neutral atom. The mass number is equal to the sum of the number of protons and the number of neutrons.
For \[_{\text{1}}{{\text{H}}^{\text{1}}}\] nucleus, the atomic number is 1 and the mass number is also 1.
Thus, one \[_{\text{1}}{{\text{H}}^{\text{1}}}\] nucleus contains one proton and zero neutrons. This is because the atomic number of 1 gives 1 proton, and the number of neutrons is equal to the difference between the mass number and atomic number. It is equal to \[{\text{1}} - {\text{1 = 0}}\] .

\[\dfrac{{\text{n}}}{{\text{p}}}\] ratio is also called neutron to proton ratio. It is the ratio of the number of neutrons to the number of protons. For \[_{\text{1}}{{\text{H}}^{\text{1}}}\] nucleus, \[\dfrac{{\text{n}}}{{\text{p}}}{\text{ = }}\dfrac{0}{1}{\text{ = 0}}\] . Hence, for \[_{\text{1}}{{\text{H}}^{\text{1}}}\] nucleus, the \[\dfrac{{\text{n}}}{{\text{p}}}\] ratio is equal to zero.

Hence, the correct option is the option (D) zero.

Note: Isotopes are the atoms of the same element with same atomic number but different mass numbers. The isotopes of the same element are atoms having the same number of protons and same number of electrons but different number of neutrons.