JEE Main Chemistry - Energetics
Exam Duration: 60 Mins Total Questions : 30
For an exothermic reaction \(\Delta\)H is
- (a)
zero
- (b)
negative
- (c)
positive
- (d)
non-predictable
What is \(\Delta\)E for system that does 500 cal of work on surroundings and 300 cal of heat is absoubed by the system?
- (a)
- 200 cal
- (b)
-300 cal
- (c)
+ 200 cal
- (d)
+ 300 cal
Given the reaction at 975\(?\) and 1 atm \(Ca{ CO }_{ 3 }\rightleftharpoons Cao(s)+{ CO }_{ 2 }(g);\Delta H=176kJ\) then \(\Delta\)E is equal to
- (a)
162 kJ
- (b)
165.6 kJ
- (c)
180 kJ
- (d)
186.4 kJ
Which one of the following statements is true for the spontaneous process?
- (a)
\(\Delta\)G increases
- (b)
\(\Delta\)G decreases
- (c)
S decreases
- (d)
\(\Delta\)S = 0
For the chamical reaciton in forward direction at 25\(?\). A + B \(\rightarrow\) AB
- (a)
\(\Delta\)S is positive
- (b)
\(\Delta\)S is negative
- (c)
\(\Delta\)S is 0
- (d)
\(\Delta\)S cannot be predicted
Given that \(\Delta\)H of the formation of CO2 (g) is - 393.13 kJ mole-1 and \(\Delta\)H of the formation of CO(g) is - 110.39 kJ mole-1. The \(\Delta\)H for the raction : \(CO(g)+1/2{ O }_{ 2 }\rightarrow { CO }_{ 2 }(g)\) would be
- (a)
- 282.74 kJ
- (b)
- 393.13 kJ
- (c)
- 503.63 kJ
- (d)
+ 282.74 kJ
The molar heats of combustion of C2H4(g), C (graphite) and H2(g) are 310.62 kcal, 94.05 kcal and 68.32 kcal, respectively. The standard heat of formation of C2H4(g) would be
- (a)
+ 108.4 kcal
- (b)
- 54.2 kcal
- (c)
+ 54.2 kcal
- (d)
- 108.4 kcal
Given the following C(s) \(\rightarrow\) C(g); \(\Delta\)H = 170.9 kcal mol-1
\(\frac { 1 }{ 2 } { H }_{ 2 }(g)\rightarrow H(g)\) , \(\Delta\)H = 170.9 kcal mol-1
\(\Delta\)Hr (CH4) = 170.9 kcal mol-1
The average C - H bond energy in CH4 would be
- (a)
+ 99.2 kcal
- (b)
- 99.2 kcal
- (c)
+ 24.5 kcal
- (d)
- 24.5 kcal
In an oven, using coal (assume the coal is 80% carbon in weigh), insufficient oxygen is supplied such that 60% of carbon is converted to CO2 and 40% carbon is converted to CO. The heat generated, when coal is burnt in theis fasion would be Given :
\(C(s)+{ O }_{ 2 }(s)\rightarrow { CO }_{ 2 }(g)+394kJ\\ C(s)+\frac { 1 }{ 2 } { O }_{ 2 }(s)\rightarrow { CO }(g)+111kJ\)
- (a)
183,200 kJ
- (b)
187,200 kJ
- (c)
185,200 kJ
- (d)
181,200 kJ
The free energy changes \(\Delta G^o\) for the reaction would be : \({ CH }_{ 3 }COOH(l)+{ C }_{ 2 }{ H }_{ 5 }OH(l)\rightarrow \)\({ CH }_{ 3 }COO{ C }_{ 2 }{ H }_{ 5 }(l)+{ H }_{ 2 }O(l)\)
(Given K for the above reaction = 4)
- (a)
- 3.473 kJ mol-1
- (b)
+ 3.473 kJ mol-1
- (c)
+ 1.473 kJ mol-1
- (d)
- 1.473 kJ mol-1
In thermodynamics a process is called reversible when
- (a)
surroundings and system change into each other
- (b)
there is no boundary between system and surroundings
- (c)
the surroundings are always in equilibrium with the system
- (d)
the system changes into the surroundings spontaneously
The heat of neutralisation of HCl and NaOH under certain condition is - 55.9 kJ and that of HCN by KOH is - 12.1 kJ. The heat of ionisation of HCN is
- (a)
- 68 kJ mol-1
- (b)
- 43.8 kJ mol-1
- (c)
68.8 kJ mol-1
- (d)
43.8 kJ mol-1
The Hess's law is an application of
- (a)
first law of thermodynamics
- (b)
second law of thermodynamics
- (c)
entropy change
- (d)
free change
Which of the following is correct for the first law of thermodynamics?
- (a)
W = \(\Delta\)E - q
- (b)
\(\Delta\)E = q - w
- (c)
\(\Delta\)E = q + w
- (d)
\(\Delta\)E = q + Pr
\({ H }_{ 2 }(g)+{ Cl }_{ 2 }(g)\rightarrow 2HCl;\Delta H=-44?.\)
\(2Na(s)+2HCl(g)\rightarrow 2NaCl(s)+{ H }_{ 2 }(g);\Delta H=-152?.\)
For the reaction \(Na(s)+1/2{ Cl }_{ 2 }(g)\rightarrow NaCl(s)\), \(\Delta H\) = ?
- (a)
54 kcal
- (b)
- 98 kcal
- (c)
- 196 kcal
- (d)
- 108 kcal
The entropy change involved in the isothermal reversible expansion of 5 moles of an ideal gas from a volume of 10 litres to 100 litres at 300 K would be
- (a)
26.88 cal degree-1
- (b)
27.88 cal degree-1
- (c)
22.88 cal degree-1
- (d)
36.88 cal degree-1
Evaporation of water is
- (a)
an exothermic change
- (b)
an endothermic change
- (c)
a process where no heat changes occur
- (d)
a process accompained by chemical reaction
\(\Delta\)H (neutralisation) is always
- (a)
+ ve
- (b)
- ve
- (c)
0
- (d)
+ ve or - ve
The enthalpy of vaporisation of water is 186.5 J mol-1; the entropy of its vaporisation would be
- (a)
0.5 J K-1 mol-1
- (b)
1.0 J K-1 mol-1
- (c)
1.5 J K-1 mol-1
- (d)
2.0 J K-1 mol-1
Given : C (diamond) + O2 \(\rightarrow\) CO2 ; \(\Delta\)H = - 395 kJ C (graphic) + O2 \(\rightarrow\) CO2 ; \(\Delta\)H = - 395 kJ The heat of formation of diamond from graphite is
- (a)
+ 2.0 kJ
- (b)
- 1.5 kJ
- (c)
- 7.88 kJ
- (d)
+ 78.8 kJ
Which of the following equations represents standard heat of formation of methene?
- (a)
C (diamond) + 2H2 (g) \(\rightarrow\) CH4(g)
- (b)
C (graphite) + 2H2 (g) \(\rightarrow\) CH4(g)
- (c)
C (diamond) + 4H (g) \(\rightarrow\) CH4(g)
- (d)
C (graphite) + 4H (g) \(\rightarrow\) CH4(g)
For a process to be spontaneous
- (a)
the entropy of the system must increse
- (b)
the entropy of the surroundings must increse
- (c)
the entropy of the surroundings must decrese
- (d)
the entropy of the universe must increse
The molar enthalpy of formation of CO2 is equal to
- (a)
zero
- (b)
molar heat of combustion of diamond
- (c)
the sum of molar enthalpies of formation CO(g) and O2(g)
- (d)
the molar heat of combustion of CO(g).
Energy can transfar from system t o surroundings as work if
- (a)
pressure of system > atmospheric pressure
- (b)
there is thermal equilibrium between system nd surroundings
- (c)
there is mechanical equilibrium between system nd surroundings
- (d)
NONE OF THESE
The efficiency of a heat engine is maximum when
- (a)
temperature difference of source and sink is minimum
- (b)
temperature difference of source and sink is maximum
- (c)
temperature of source is greater than that of sink
- (d)
temperature of sink is greater than that of source.
"When a system A is an thermal equilibrium with B and B is in thermal equilibrium with C, then A and C are in equilibrium with each other". This is a statement of
- (a)
zeroth law of thermodynamics
- (b)
first law of thermodynamics
- (c)
second law of thermodynamics
- (d)
third law of thermodynamics
The heats of neutralisation of four acids A, B, C and D when neutralised against a common base are 13.7, 9.4, 11.2 and 12.4 kcal respectively. The weakest among these acids is
- (a)
D
- (b)
C
- (c)
B
- (d)
A
Which of the following expressions defines the physical significance of free energy change?
- (a)
\(\Delta\)G = W (expansion)
- (b)
-\(\Delta\)G = W (non-expansion)
- (c)
-\(\Delta\)G = - W (non-expansion)
- (d)
\(\Delta\)G = - W (expansion)
A heat engine absoubs heat Q1 at temperature T1, and heat Q2 at temperature T2. Work done by the enge is (Q1 + Q2) J. This data
- (a)
violates 1st law of the thermodynamics
- (b)
violates 1st law of the thermodynamics if Q1 is -ve
- (c)
violates 1st law of the thermodynamics if Q2 is +ve
- (d)
does not violates 1st law of the thermodynamics.
A 1.250 g sample of octane (C8H18) is burnt in excess of oxygen in bomb calorimeter. The temperature of calorimeter rises from 294.05 to 300.78 K. If heat capacity of the calorimeter is 8.93 kJ K-1, the heat transferred to the calorimeter would be
- (a)
0.001 kJ
- (b)
0.025 kJ
- (c)
0.55 kJ
- (d)
0.075 kJ