Question

A sample of phosphorous trichloride $\left(PC{l}_3\right)$ contains $1.4$ moles of the substance. How many atoms are there in the sample ?

• A. $4$
• B. $5.6$
• C. $8.431\times {10}^{23}$
• D. $3.372\times {10}^{24}$
• E. $2.409\times {10}^{24}$

Answer 1

Answer: (D)

$3.372\times {10}^{24}$

Given that,

$PC{l}_3=1.4moles$

We know that,

$1mole=6.022\times {10}^{23}particles$

So,

Number of molecules in $1.4molPC{l}_3=1.4\times 6.022\times {10}^{23}=8.431\times {10}^{23}$

In $PC{l}_3$ contains $4$ atoms: $1Patom$ and $3Clatoms$

Therefore

Number of atoms in $1.4molPC{l}_3=8.431\times {10}^{23}\times 4=33.72\times {10}^{23}=3.372\times {10}^{24}$

Hence,

In 1.4 moles of $PC{l}_3$ sample have $3.372\times {10}^{24}$ atoms.