71. Consider the following results for the thermal decomposition of acetaldehyde in a closed vessel.
What is the order of the reaction?
(a) Zero order
(b) First order
(c) Second order
(d) Third order

Answer: (c)

72. A reversible liquid phase endothermic reaction is to be carried out in a plug flow reactor. For minimum reactor volume, it should be operated such that, temperature along the length will
(a) Decrease
(b) Increase
(c) Be at the highest allowable temperature throughout
(d) First increases and then decreases

Answer: (c)

73. A plug flow reactor is characterized by
(a) Presence of axial mixing
(b) High capacity
(c) Constant concentration throughout the reactor
(d) Presence of lateral mixing

Answer: (d)

74. Which one of the following order reaction is independent of initial concentration?

Answer: (c)

75. For the process of continuous constant-pressure combustion of a fuel with oxygen taking place in a well insulated space
(a) 𝑄=Δ 𝐻
(b) 𝑄<Δ 𝐻
(c) 𝑄>Δ 𝐻
(d) 𝑄=Δ 𝐻=0

Answer: (d)

76. Which one of the following is slow, low temperature and flameless form of combustion sustained by the heat evolved when oxygen directly affects the surface of a condensed-phase fuel?
(a) Pyrolysis
(b) Turbulence
(c) Quenching
(d) Smoldering

Answer: (d)

77. The gross and net calorific values of a fuel will be the same:
(a) If its ash content is zero
(b) If its carbon content is low
(c) If its hydrogen content is zero
(d) Under no circumstances

Answer: (c)

78. Which one of the following is the correct sequence in increasing order for knocking tendencies?
(a) Naphthalene < isooctane < n-octane
(b) Isooctane < Naphthalene < n-octane
(c) Naphthalene < n-octane < isooctane
(d) Isooctane < n-octane< Naphthalene

Answer: (d)

79. Consider the following combustion reaction of cycloalkanes: 
What is the correct order of heat energy liberated per mole for complete combustion of cycloalkanes with variation of 𝑛𝑛?
(a) 𝑛=3>𝑛=4>𝑛=5>𝑛=6
(b) 𝑛=6>𝑛=4>𝑛=5>𝑛=3
(c) 𝑛=3≈𝑛=4>𝑛=5>𝑛=6
(d) 𝑛=6>𝑛=4>𝑛=5≈𝑛=3

Answer: (a)

80. Which of the following metals have poor affinity for oxygen than iron, and cannot be removed through oxidation and hence they must be controlled by introducing pig iron?
(a) Ni and Cu
(b) Ca and Cr
(c) Ni and Cr
(d) Ca and Mg

Answer: (d)