Question

Among $ 10^{-10} $ g (each) of the following elements, which one will have the highest number of atoms? 
Element : Pb, Po, Pr and Pt

• A. Po
• B. Pr
• C. Pb
• D. Pt

Hint:

The number of atoms in a given mass is inversely proportional to the molar mass of the element.

Answer 1

The Correct Option is B

$\text{No. of atoms} = \frac{\text{Mass in g}}{\text{Molar Mass (g/mol)}} \times N_A$

Therefore for the same Mass element having the least Molar mass will have the higher no. of atoms.

$M_{Pb} = 209$
$M_{Pr} = 141$
$M_{Po} = 207$
$M_{Pt} = 195$