A metal has an fcc latticed.The edge length of the unit cell is `404` pm .The density of the metal is `2.72 g//cm^(-3)` .The molar mass of the metal is
`(N_(A)` Avogadro's constant `= 6.2 xx 10^(23) mol^(-1))`

Options

A. `27 g mol^(-1)`
B. `20 g mol^(-1)`
C. `40 g mol^(-1)`
D. `30 g mol^(-1)`

Answer

A

Explanation

`d = (Z xx M)/(a^3 xx N_A)`
`d = 2.72 g cm^(-3) , Z = 4`,
`a = 404 " pm " = 4.04 xx 10^(-8) cm`
`2.72 = (4 xx M)/((4.04 xx 10^(-8))^(3) xx 6.02 xx 10^(23)`
or `M = 27 g mol^(-1)`.