The atomic weight of an element is 39.The number of neutrons in its nucleus is one more than the number of protons. The number of protons, neutrons and electrons respectively in its atom would be

Options

A. 19,20,19
B. 19,19,20
C. 20,21,19
D. 20,19,20

Answer

A

Explanation

Mass number = Number of protons + Number of neutrons
`39 = x + (x +1)` (x =Number of protons )
` :. " " 2x = 39-1 = 38`
` :. " " x = 19`
Electrons = 19
Protons = 19
Neutrons = 20