Question

The number of quanta of radiation of frequency $4.98\times {10}^{14}{s}^{-1}$ required to melt 100 g of ice are (latent heat of melting of ice is 33 joule per g):

• A. ${10}^{20}$
• B. ${10}^{22}$
• C. ${10}^{24}$
• D. $6.023\times {10}^{21}$

Answer 1

The correct option is B ${10}^{22}$

$1g$ requires $33J$. So, $100g$ will require $3300J$ heat.

Total quanta,

E=hv

$=6.62\times {10}^{-34}\times 4.98\times {10}^{14}=32.97\times {10}^{-20}$

$100g$ of ice will require=$\frac{3300}{32.97\times {10}^{-20}}=100.09$

$100$quantal=${10}^{22}J$