For a carnot engine, the source is at 500 K and the sink at 300 K. What is efficiency of this engine [BHU 2004]

(1) 0.2

(2) 0.4

(3) 0.6

(4) 0.3

Concept Questions :-

Enthalpy and It's Type
High Yielding Test Series + Question Bank - NEET 2020

Difficulty Level:

From Kirchhoff's equation which factor affects the heat of reaction [MP PMT 1990]

(1) Pressure

(2) Temperature

(3) Volume

(4) Molecularity

Concept Questions :-

Thermodynamics' Properties and process
High Yielding Test Series + Question Bank - NEET 2020

Difficulty Level:

The absolute enthalphy of neutralisation of the reaction $MgO\left(s\right)+2HCl\left(aq\right)\to MgC{l}_{2}\left(aq\right)+{H}_{2}O\left(l\right)$ will be [CBSE PMT 2005]

(1) Less than –57.33 kJ mol–1

(2) –57.33 kJ mol–1

(3) Greater than –57.33 kJ mol–1

(4) 57.33 kJ mol–1

Concept Questions :-

Hess's Law
High Yielding Test Series + Question Bank - NEET 2020

Difficulty Level:

The heat of transition (ΔHt) of graphite into diamond would be, where

$C\left(\text{graphite}\right)+{O}_{2}\left(g\right)\to C{O}_{2}\left(g\right);\text{\hspace{0.17em}\hspace{0.17em}}\Delta H=x\text{\hspace{0.17em}}kJ$

$C\left(\text{diamond}\right)\text{\hspace{0.17em}}+{C}_{2}\left(g\right)\to C{O}_{2}\left(g\right);\text{\hspace{0.17em}\hspace{0.17em}}\Delta H=y\text{\hspace{0.17em}}kJ$ [Pb. PET 1985]

(1) $\left(x+y\right)\text{\hspace{0.17em}}kJ\text{\hspace{0.17em}}mo{l}^{-1}$

(2) $\left(x-y\right)\text{\hspace{0.17em}}kJ\text{\hspace{0.17em}}mo{l}^{-1}$

(3) $\left(y-x\right)\text{\hspace{0.17em}}kJ\text{\hspace{0.17em}}mo{l}^{-1}$

(4) None of these

Concept Questions :-

Thermochemistry
High Yielding Test Series + Question Bank - NEET 2020

Difficulty Level:

Given that

$2C\left(s\right)+2{O}_{2}\left(g\right)\to 2C{O}_{2}\left(g\right);\text{\hspace{0.17em}\hspace{0.17em}}\Delta H=-787\text{\hspace{0.17em}}kJ$

${H}_{2}\left(g\right)+\frac{1}{2}{O}_{2}\left(g\right)\to {H}_{2}O\left(l\right);\text{\hspace{0.17em}\hspace{0.17em}}\Delta H=-286\text{\hspace{0.17em}}kJ$

${C}_{2}{H}_{2}\left(g\right)+2\frac{1}{2}{O}_{2}\left(g\right)\to 2C{O}_{2}\left(g\right)+{H}_{2}O\left(l\right);\text{\hspace{0.17em}}\Delta H=-1301\text{\hspace{0.17em}}kJ$

Heat of formation of acetylene is [KCET 1989; Orissa JEE 2005]

(1) –1802 kJ

(2) +1802 kJ

(3) –800 kJ

(4) +228 kJ

Concept Questions :-

Hess's Law
High Yielding Test Series + Question Bank - NEET 2020

Difficulty Level:

The enthalpy of combustion at 25°C of H2, cyclohexane (C6H12) and cyclohexene (C6H10) are –241, –3920 and –3800 KJ / mole respectively. The heat of hydrogenation of cyclohexene is [BHU 2005]

(1) – 121 KJ / mole

(2) + 121 KJ / mole

(3) – 242 KJ / mole

(4) + 242 KJ / mole

Concept Questions :-

Hess's Law
High Yielding Test Series + Question Bank - NEET 2020

Difficulty Level:

The heat change for the reaction ${H}_{2}+\frac{1}{2}{O}_{2}\to {H}_{2}O$ is called

(1) Heat of reaction

(2) Heat of formation

(3) Heat of vaporisation

(4) None of the above

Concept Questions :-

Thermochemistry
High Yielding Test Series + Question Bank - NEET 2020

Difficulty Level:

The heat of neutralisation of a strong acid and a strong alkali is 57.0 kJ mol–1. The heat released when 0.5 mole of HNO3 solution is mixed with 0.2 mole of KOH is [KCET 1991; AIIMS 2002;

(1) 57.0 kJ

(2) 11.4 kJ

(3) 28.5 kJ

(4) 34.9 kJ

Concept Questions :-

Thermochemistry
High Yielding Test Series + Question Bank - NEET 2020

Difficulty Level:

A solution of 500 ml of 0.2 M KOH and 500 ml of 0.2 M HCl is mixed and stirred; the rise in temperature is T1. The experiment is repeated using 250 ml each of solution, the temperature raised is T2. Which of the following is true [EAMCET 1987; MP PET 1994]

(1) T1 = T2

(2) T1 = 2T2

(3) T1 = 4T2

(4) T2 = 9T1

Concept Questions :-

Enthalpy and It's Type
High Yielding Test Series + Question Bank - NEET 2020

Difficulty Level:

In the reaction for the transition of carbon in the diamond form to carbon in the graphite form, ΔH is –453.5 cal. This points out that [BHU 1981; KCET 1986, 89]

(1) Graphite is chemically different from diamond

(2) Graphite is as stable as diamond

(3) Graphite is more stable than diamond

(4) Diamond is more stable than graphite

Concept Questions :-

Thermochemistry