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 in `1 cm^(3) Ag = 10.5 g`
No. of atoms in `1 cm^(3) = (10.5)/(108) N_A`
No. of atoms in 1 cm = `((10.5)/(108) N_A))^(1//3)`
No. of atoms in `1 cm^2 = ((10.5)/(108)N_A)^(2//3)`
No. of atoms in `10^(-12) m^2 " or " 10^(-8) cm^2`
`= ((10.5)/(108)N_A))^(2//3) xx 10^(-8)`
`= ((10.5 xx 6.022 xx 10^(23))/(108))^(2//3) xx 10^(-8)`
`= 1.50 xx 10^7`
`x = 7`.