Question

Isotone of ${}_{32}^{76}Ge$ is/are:

• A. ${}_{32}^{77}Ge$
• B. ${}_{33}^{77}As$
• C. ${}_{34}^{77}Se$
• D. ${}_{34}^{78}Se$

Answer 1

Answer: (B), (D)

${}_{34}^{78}Se$

Isotones are the elements which have the same number of neutrons and different number of protons.
Number of neutrons = mass number - atomic number of the element
${}_{32}^{76}Ge$: number of neutrons = $76-32$ = 44
For option (a)
${}_{32}^{77}Ge$: number of neutrons = $77-32$ = 45
For option (b)
${}_{33}^{77}As$: number of neutrons = $77-33$ = 44
For option (c)
${}_{34}^{77}Se$: number of neutrons = $77-34$ = 43
For option (d)
${}_{34}^{78}Se$: number of neutrons = $78-34$ = 44