Q. How much heat energy is gained when $5\ kg$ of water at $20℃$ is brought to its boiling point (specific heat of water $= 4.2\ kJ\ kg^{- 1}c^{- 1}$)
A) $1680\ kJ$
B) $1700\ kJ$
C) $1720\ kJ$
D) $1740\ kJ$
Explanation
(a) $Q = m.c.\mathrm{\Delta}\theta = 5 \times (1000 \times 4.2) \times (100 - 20)$
$= 1680 \times 10^{3}J = 1680kJ$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.