# The three stable isotopes of neon: Ne1020Ne, Ne1021Ne and Ne1022Ne have respective abundances of 90.51%, 0.27% and 9.22%. - Physics

Numerical

The three stable isotopes of neon: ""_10^20"Ne", ""_10^21"Ne" and ""_10^22"Ne" have respective abundances of 90.51%, 0.27% and 9.22%. The atomic masses of the three isotopes are 19.99 u, 20.99 u and 21.99 u, respectively. Obtain the average atomic mass of neon.

#### Solution

Atomic mass of ""_10^20"Ne", m1 = 19.99 u

Abundance of ""_10^20"Ne", η= 90.51%

Atomic mass of ""_10^21"Ne", m= 20.99 u

Abundance of ""_10^21"Ne", η= 0.27%

Atomic mass of ""_10^22"Ne", m= 21.99 u

Abundance of ""_10^22"Ne", η3 = 9.22%

The average atomic mass of neon is given as:

"m" = ("m"_1η_1 + "m"_2η_2 + "m"_3η_3)/(η_1 + η_2 + η_3)

= (19.99 xx 90.51 + 20.99 xx 0.27 + 21.99 xx 9.22)/(90.51 + 0.27 + 9.22)

= 20.1771 u

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Chapter 13: Nuclei - Exercise [Page 462]

#### APPEARS IN

NCERT Physics Class 12
Chapter 13 Nuclei
Exercise | Q 13.2 | Page 462
NCERT Physics Class 12
Chapter 13 Nuclei
Exercise | Q 2 | Page 462

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