Question

Atomic number of an element is 42. Find out the number of electrons present in the valence shell.

• A. 1
• B. 3
• C. 2
• D. 4

Answer 1

The correct option is A 1

Molybdenum is the element with atomic number 42 and is having electronic configuration $\left[Kr\right]5s^{1}4d^5$, where atomic no. of Kr $=$ 36. Thus no. of valence electrons is 1, which is no of an electron in 5s subshell.