Question

How much heat energy is gained when $5kg$ of water ${20}^{o}C$ is brought to its boiling point (Specific heat of water $=4.2kJk{g}^{-1}$

• A. $1680kJ$
• B. $1700kJ$
• C. $1720kJ$
• D. $1740kJ$

Answer 1

The correct option is A $1680kJ$

It is known that Heat Q for change in temperature is given by $Q=m.c\Delta \theta$

according to question:

$Q=m.c.\Delta \theta =5\times (1000\times 4.2)\times (100-20)$

$=1680\times {10}^{3}J=1680kJ$