Question

The no of neutrons in 5g of D2O ?

Answer 1

Answer : The number of neutrons in 5 g of $D_2O$ is $1.5055\times 10^{24}$ neutrons.

Solution : Given,

Mass of $D_2O$ = 5 g

Molar mass of $D_2O$ = 20 g/mole

First we have to calculate the moles of $D_2O$.

$\text{ Moles of }D_2O=\frac{\text{ Given mass of }D_2O}{\text{ Molar mass of }D_2O}=\frac{5g}{20g/mole}=0.25mole$

1 mole of $D_2O$ has $6.022\times 10^{23}$ molecule of $D_2O$

0.25 moles of $D_2O$ has $(6.022\times 10^{23})\times (0.25)=1.5055\times 10^{23}$ molecule of $D_2O$

Now we have to calculate the number of neutrons in $D_2O$.

The number of neutrons present in 1 molecule of $D_2O$ is,

Number of neutrons = Atomic mass - Atomic number = 20 - 10 = 10 neutrons

Number of neutrons present in 1 molecule of $D_2O$ = 10 neutrons

Number of neutrons present in $1.5055\times 10^{23}$ molecule of $D_2O$ = $1.5055\times 10^{24}$ neutrons

Therefore, the number of neutrons in 9 mg of $D_2O$ is $1.5055\times 10^{24}$ neutrons.

Answer 2

Explanation:

see the Image  ( d2o= 2*2+16=16 )