Question

The temperature of $100g$ of water is to be raised from ${24}^{0}C$ to ${90}^{0}C$ by adding steam to it. The mass of the steam required for this purpose is roughly :

• A. $10g$
• B. $12g$
• C. $14g$
• D. $16g$

Answer 1

The correct option is B $12g$

Heat energy required to bring water from ${24}^o$C to ${90}^o$C is :
$H=m.s.\Delta T$ $=100\times 1\times (90-24)=6600cal$.
Amount of steam required for this heat energy is:
$6600=m\left(540\right)$ [$L_s=540cal/g$]
$m=12.22g$