Question

If the atomic mass of $Li$ and $Cl$ are $7$ and $35.5amu$ respectively, then what would be number of $LiCl$ molecule in cube of $LiCl$ with $length\times height\times breadth=1\times 1\times 1=1c{m}^3$?

• A. Nearly $2.5\times {10}^{22}$
• B. Nearly $4\times {10}^{20}$
• C. Nearly $12\times {10}^{30}$
• D. Nearly $14\times {10}^{23}$

Answer 1

The correct option is A Nearly $2.5\times {10}^{22}$

Total Atomic mass $=7+35.5=42.5amu$

No. of LiCl molecules $=42.5\times 6.022\times {10}^{23}\times {10}^{-6}$

$=255.935\times {10}^{23}\times {10}^{-6}$

$\approx 2.5\times {10}^{22}$ molecules