Question

Which of the following letter has a value of $7$?

Isotope	p	n	$e^{-}$	mass #	Atomic #
${}^{16}O$	A
${}^{13}C$		B
${}^{23}Na$			C
${}^{10}B$				D

• A. A
• B. B
• C. C
• D. D
• E. E

Answer 1

The correct option is B B

A is no of protons in $O$ and it is 8 as its atomic no is 8
B is no of neutrons. so its $13-6$ = 7
C is no of electrons is 11 as its atomic no is $11$
D has mass no $10$
So the correct option is B with 7 neutrons