Question

Number of electrons in 1.8 mL of $H_{2}O$ are:

• A. $6.02\times {10}^{23}$
• B. $3.01\times {10}^{24}$
• C. $1.8\times {10}^{23}$
• D. $6.02\times {10}^{25}$

Answer 1

Answer: (A)

$6.02\times {10}^{23}$

There is a total of 10 electrons in 1 $H_{2}O$ Molecule (2 electrons from hydrogen and 8 electrons from oxygen.)

moles of $H_{2}O\left(n\right)=\frac{massofsubstance}{motormass}$

18 g of $H_{2}O$ = 1 mole
mass of 1.8 ml of $H_{2}O=1.8ml\times 1g/ml=1.8g$ [$\because Densityof{H}_{2}O=1g/ml$]
1.8 g of water = 0.1 moles of water

Therefore, 1.8 ml of $H_{2}O$ means 0.1 mole of $H_{2}O$

Number of molecules = n$\times$ Avogadro Number

Number of molecules = $0.1\times 6.022\times {10}^{23}$

$=0.6022\times {10}^{23}$

Number of electron in total molecules of $H_{2}O$ $=0.6022\times {10}^{23}\times 10$

Number of electron in total molecules of $H_{2}O$ $=6.022\times {10}^{23}$

Option $A$ is correct.