Question

What is the mass in grams of 1.5*10^-3 mol of sodium

Answer 1

So n:m/M

m=nxM

Sodium=1.05x10-³x(23.0)

= 2.42x10-²grams

Lead= 1.05x10-³x (207.2)

=2.1756x10-¹ grams

Valium= 0.5x10-³ x (12.0x16 + 1.0x 13 +

12.0 + 126.9 + 14.0 x 2 + 16.0)

=1.94x10-¹ grams

Answer 2

The Formula to find the number of moles is:
Number of Moles = Mass/ Molar Mass

Which means that Mass = Number of Moles * Molar Mass

We know that Number of Moles of Sodium Na = $1.5*10^_{-3}$ moles 
If you check the Periodic Table, Molar Mass of Sodium Na = 23g/mol

So, Mass = $1.5*10^_{-3} * 23$ = $3.45 * 10^{-2}$ 

So, the mass in grams of  $1.5*10^_{-3}$ mol of Sodium is $3.45 * 10^{-2}$

Hope this Helps :)