Question

which is the correct symbol for the atom with 42 protons and 49 neutrons?
o a) \\( \frac { 91 } { 42 } m o \\)
o b) \\( \frac { 49 } { 42 } i n \\)
o c) \\( \frac { 91 } { 49 } m o \\)
o d) \\( \frac { 91 } { 42 } i n \\)

Explanation:

Step1: Determine the atomic number

The atomic number \(Z\) is equal to the number of protons. Given there are 42 protons, so \(Z = 42\).

Step2: Determine the mass number

The mass number \(A\) is the sum of protons and neutrons. So \(A=42 + 49=91\).

Step3: Identify the element

Looking at the periodic table, the element with atomic number \(Z = 42\) is Molybdenum (\(Mo\)).

Step4: Write the nuclide symbol

The nuclide symbol is written as \(_{Z}^{A}\text{Element Symbol}\), so it is \(_{42}^{91}Mo\).

Answer:

A. \(_{42}^{91}Mo\)