Question:
Enthalpy change is always negative for which one of the following processes?
Enthalpy change is always negative for which one of the following processes?
Show Hint
Combustion reactions always release energy, hence \( \Delta H<0 \).
Updated On: Apr 24, 2026
- Enthalpy of ionisation
- Enthalpy of sublimation
- Enthalpy of vapourisation
- Enthalpy of bond dissolution
- Enthalpy of combustion
Show Solution
Verified By Collegedunia
The Correct Option is
Solution and Explanation
Concept:
• Endothermic processes $\rightarrow$ \( \Delta H>0 \)
• Exothermic processes $\rightarrow$ \( \Delta H<0 \)
Step 1: Identify nature of each process.
• Ionisation $\rightarrow$ Endothermic
• Sublimation $\rightarrow$ Endothermic
• Vapourisation $\rightarrow$ Endothermic
• Bond dissociation $\rightarrow$ Endothermic
• Combustion $\rightarrow$ Exothermic
Step 2: Select process with negative enthalpy.
Only combustion always releases heat.
• Endothermic processes $\rightarrow$ \( \Delta H>0 \)
• Exothermic processes $\rightarrow$ \( \Delta H<0 \)
Step 1: Identify nature of each process.
• Ionisation $\rightarrow$ Endothermic
• Sublimation $\rightarrow$ Endothermic
• Vapourisation $\rightarrow$ Endothermic
• Bond dissociation $\rightarrow$ Endothermic
• Combustion $\rightarrow$ Exothermic
Step 2: Select process with negative enthalpy.
Only combustion always releases heat.
Was this answer helpful?
0
0
Top KEAM Chemistry Questions
- The pH of a solution obtained by mixing 60 mL of 0.1 M BaOH solution at 40m of 0.15m HCI solution is
- $4\, g$ of copper was dissolved in concentrated nitric acid. The copper nitrate solution on strong heating gave $5\, g$ of its oxide. The equivalent weight of copper is :
- Green chemistry deals with
- Neopentyl bromide undergoes dehydrohalogenation to give alkenes even though it has no $\beta$- hydrogen. This is due to
- Plot of $ log\text{ }x/m $ against log $p$ is a straight line inclined at an angle of $ 45{}^\circ $ . When the pressure is $ 0.5 \,arm $ and Freundlich parameter. $ k $ is $ 10 $ , the amount of solute adsorbed per gram of adsorbent will be $ (log\text{ }5=0.6990) $
View More Questions
Top KEAM Work done in Thermodynamics Questions
- In the reaction \( \frac{3}{2}O_2(g) \rightarrow O_3(g) \), the value of \( \Delta_r G^\circ \) at \( 298\,K \) is approximately ( \( K_p = 10^{-30},\ 2.303RT = 5.7\,\text{kJ mol}^{-1} \) )
- \( \Delta G \) for \( 3\text{X}_{(g)} + 2\text{Y}_{(g)} \rightarrow 3\text{Z}_{(g)} \) at 293 K is
( \( \Delta H^\circ = -13\,\text{kJ mol}^{-1} \), \( \Delta S^\circ = -45\,\text{J mol}^{-1}\text{K}^{-1} \) ) - An ideal gas is allowed to expand from 1 L to 10 L against a constant external pressure of 1 bar. The work done is [1 bar = 100 J]}
- What are the thermodynamic conditions for a reaction to be spontaneous at low temperature and non-spontaneous at high temperature?
- Consider the following thermodynamic properties of a system: (i) Volume (ii) Pressure (iii) Density (iv) Heat capacity. The extensive property/properties of the system is/are
View More Questions
Top KEAM Questions
- i.$\quad$ They help in respiration ii.$\quad$ They help in cell wall formation iii.$\quad$ They help in DNA replication iv. $\quad$They increase surface area of plasma membrane Which of the following prokaryotic structures has all the above roles?
- A body oscillates with SHM according to the equation (in SI units), $x = 5 cos \left(2\pi t +\frac{\pi}{4}\right) .$ Its instantaneous displacement at $t = 1$ second is
- The pH of a solution obtained by mixing 60 mL of 0.1 M BaOH solution at 40m of 0.15m HCI solution is
Kepler's second law (law of areas) of planetary motion leads to law of conservation of
- If $\int e^{2x}f' \left(x\right)dx =g \left(x\right)$, then $ \int\left(e^{2x}f\left(x\right) + e^{2x} f' \left(x\right)\right)dx =$
View More Questions