Question

The number of potassium atoms present in $117$ g of potassium sample (Molecular Weight $=39$ g/mole) is:

• A. $9\times 6.023\times {10}^{23}$ atoms
• B. $7\times 6.023\times {10}^{23}$ atoms
• C. $4\times 6.023\times {10}^{23}$ atoms
• D. $3\times 6.023\times {10}^{23}$ atoms

Answer 1

The correct option is D $3\times 6.023\times {10}^{23}$ atoms

As we know, one mole of each substance contains $N_A=6.023\times {10}^{23}$ atoms.

Here, moles of $K$ $=\frac{117}{39}=3$

$\therefore$ atoms of $K$ $=3N_A=3\times 6.023\times {10}^{23}$ atoms

Hence, option D is correct.