Assertion (A) : Steam is more harmful for human body than the boiling water in case of burn. Reason (R) : Boiling water contains more heat than steam.

Assertion (A) is true because steam causes more severe burns than boiling water at the same temperature [t1, t2]. This is due to the latent heat of vaporization, which is the energy absorbed by water to turn into steam without a temperature increase [c2, t3]. When steam contacts the skin, it undergoes condensation, releasing this stored latent heat (approximately 2250 J/g or 40.7 kJ/mol) directly onto the tissue [t3, t5]. Reason (R) is false because steam actually contains significantly more heat energy than boiling water at 100°C [t4, t7]. While boiling water only transfers heat as it cools, steam first releases its massive latent heat during the phase change to liquid and then continues to burn the skin as 100°C water [t3, t4]. Therefore, the assertion is correct, but the reason provided is scientifically inaccurate.

Sources

1. [1] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 22: Vertical Distribution of Temperature > Latent Heat > p. 294