The relative abundance of isotopes of an element shows the composition as \[{{\,}^{200}}X=90%,{{\,}^{199}}X=8.0%,{{\,}^{202}}X=2.0%\] The average atomic mass of element is
A) 201 amu
B) 202 amu
C) 199 amu
D) 200 amu
Correct Answer:
D
Solution :
Av. Atomic mass \[=\frac{200\times 90+199\times 8+202\times 2}{100}\] = 200 amu