Assertion : `""_(14)Si^(30),""_(15)P^(31) and ""_(16)S^(32)` are a group of isotones.
Reason : Isotones are atoms of different elements having different mass numbers and atomic numbers but same number of neutrons in their nuclei.

Options

A. If both the assertion and reason are true statement and reason is correct explanation of the assertion .
B. If both the assertion and reason are true statement but reason is not a correct explanation of the assertion .
C. If the assertion is true but the reason is a false statement.
D. If both assertion and reason are false statements.

Answer

A

Explanation

Different atoms when contain same number of neutrons are called isotones.
`""_(14)Si^(30),""_(15)P^(31) an d""_(16)S^(32)` are isotones, because all of these contains 16 neutrons.
since Atomic mass =n+p
`:.` n=atomic mass -p
For ` Si to 30-4=16`
`P to 31-15=16`
`S to 32-16=16`