MHT CET202523 Apr 2025Morning ShiftChemistryThermodynamics (C)Actual
Which from following reactions is exothermic?
Options
- AKOH _ ( aq ) + HNO _ 3( aq ) KNO _ 3( aq ) + H ₂ O
- BH ₂ O _ (s) H ₂ O _ (l)
- CNaCl _ ( s ) + aq Na _ ( aq ) ⁺+ Cl _ ( aq ) ⁻
- DN _ 2( ~g ) +2 O _ 2( ~g ) 2 NO _ 2( ~g )
Correct answer
A. KOH _ ( aq ) + HNO _ 3( aq ) KNO _ 3( aq ) + H ₂ O
Step-by-step solution
The reaction is exothermic when it releases heat, indicated by a negative enthalpy change ( H Neutralization between a strong base and strong acid, such as KOH _ ( aq ) + HNO _ 3( aq ) KNO _ 3( aq ) + H ₂ O , is highly exothermic. Melting ice ( H ₂ O _ (s) H ₂ O _ (l) ) is endothermic, requiring energy input. Dissolution of NaCl ( NaCl _ ( s ) + aq Na _ ( aq ) ⁺ + Cl _ ( aq ) ⁻ ) is slightly endothermic with a net heat absorption. Formation of NO ₂ from elements ( N _ 2( g ) + 2 O _ 2( g ) 2 NO _ 2( g ) ) is endoth