Silver (atomic weight `108 g mol^(-1))` has a density of `10.5 g cm^(-3)`. The number of silver atoms on a surfaces of area `10^(-12) m^(2)` can be expressed in scientific notation as `Y xx 10^(-x)`, The value of `x` is …….

Answer

7

Explanation

Density `=("Mass")/("Volume")`
10.5 g/`cm^(3)` means 10.5 of Ag is present in `1 cm^(3)`
No. of Ag atoms in `1 cm^(3) = 10.5/108 xx 6.02 xx 10^(23)`
`=5.85 xx 10^(22)`
No. of atoms in 1 cm `=(58.5 xx 10^(21))^(1//2)`
`=3.882 xx 10^(7)`
No. of atoms in `1 cm^(2) = (3.882 xx 10^(7))^(2)`
No. of atoms in `10^(-12)m^(2)` or `10^(-8) cm^(2)`
`=(3.882 xx 10^(7))^(2) xx 10^(-8)`
`=1.506 xx 10^(7)`
Volume of x =7