The nuclei of which one of the following pairs of nuclei are isotones?

Question

The nuclei of which one of the following pairs of nuclei are isotones? (A)  34 Se 74, 31 Ga 71 (B)  38 Sr 84, 38 Sr 86 (C)  42 Mo 92, 40 Zr 92 (D)  20 Ca 40, 16 S 32

Tardigrade Admin · Accepted Answer

The isotones have same number of neutrons.
In given options

_{34} S e^{74}

has

74 - 34 = 40,

_{31} G a^{71}

has

71 - 31 = 40,

_{38} S r^{84}

has

84 - 38 = 46,

_{38} S r^{86}

has

86 - 38 = 48,

_{42} M o^{92}

has

92 - 42 = 50,

_{40} Z r^{92}

has

92 - 40 = 52,

_{20} C a^{40}

has

40 - 20 = 20

,
and

_{34} S e^{74}

has

32 - 16 = 16

neutrons.
Hence isotonic pair is of

_{34} S e^{74},_{31} G a^{71}

Q. The nuclei of which one of the following pairs of nuclei are isotones?

$_{34} S e^{74},_{31} G a^{71}$

$_{38} S r^{84},_{38} S r^{86}$

$_{42} M o^{92},_{40} Z r^{92}$

$_{20} C a^{40},_{16} S^{32}$

Q. The nuclei of which one of the following pairs of nuclei are isotones?

34​Se74,31​Ga71

38​Sr84,38​Sr86

42​Mo92,40​Zr92

20​Ca40,16​S32

$_{34} S e^{74},_{31} G a^{71}$

$_{38} S r^{84},_{38} S r^{86}$

$_{42} M o^{92},_{40} Z r^{92}$

$_{20} C a^{40},_{16} S^{32}$