Question

Calculate the number of electrons in $100grams$ of ${CO}_2$
Can a body have a charge of (a) $0.32\times {10}^{-18}C$ (b) $0.64\times {10}^{-20}C$ (c) $4.8\times {10}^{-21}C$?

Answer 1

No of moles of $C{o}_2$ in 100gm

n = $\frac{100}{44}$ = 2.28

total no. of moles = 2.28 $\times$ $N_A$

so electron will be = 22$\times$ 2.28 $\times N_A$

= 22 $\times$ 2.28 $\times$ $\times$ 6.023 $\times {10}^{23}$

= 3.02 $\times {10}^{25}$

(2)

(a)

q = ne

n$\times$ 1.6$\times {10}^{-19}$

= 0.32 $\times {10}^{-18}$ = 3.2 $\times {10}^{-17}$

n = 2 so possible

(b)

n $\times 1.6\times {10}^{19}$ = 0.64 $\times {10}^{20}$

= 0.64 $\times {10}^{-17}$

here n < 1

so not possible

(c)

n$\times 1.6\times {10}^{-19}$ = 4.8 $\times {10}^{-21}$

n = 3 $\times {10}^{-2}$

= 0.03

n < 1

so not possible