71. When carbon in the cast iron is principally in the form of graphite, the cast iron will be of
grey colour
white colour
yellow colour
brown colour
✅ The correct answer is option A.
Mechanical Engineering
Prepare with the best Mechanical Engineering MCQs with answers and explanations for exams, interviews, and job tests. Our collection covers core topics such as engineering mechanics, thermodynamics, strength of materials, theory of machines, fluid mechanics, heat transfer, manufacturing processes, machine design, and power plant engineering. These Mechanical Engineering multiple-choice questions are designed for students, fresh graduates, and professionals preparing for NTS, PPSC, FPSC, PEC exams, GATE, university entry tests, and recruitment assessments. Strengthen your technical knowledge and problem-solving ability with our updated and comprehensive Mechanical Engineering MCQs.
72. The knocking tendency in spark ignition engines can be decreased by adding dopes like tetra ethyle lead and ethylene dibromide.
Agree
Disagree
✅ The correct answer is option A.
73. In a stress-strain diagram for mild steel, as shown in the below figure, the point A represents
elastic limit
upper yield-point
lower yield point
breaking point
✅ The correct answer is option A.
74. The machine tool guide ways are usually hardened by
vacuum hardening
martempering
induction hardening
flame hardening
✅ The correct answer is option D.
75. A lead ball with a certain velocity is made to strike a wall, it falls down, but rubber ball of same mass and with same velocity strikes the same wall, it rebounds. Select the correct reason from the following:
both the balls undergo an equal change in momentum
the change in momentum suffered by rubber ball is more than the lead ball
the change in momentum suffered by rubber ball is less than the lead ball
none of the above
✅ The correct answer is option B.
76. A leaf spring in automobiles is used
to apply forces
to measure forces
to absorb shocks
to store strain energy
✅ The correct answer is option C.
77. A higher compression ratio causes
pre-ignition
increase in detonation
an acceleration in the rate of combustion
any one of these
✅ The correct answer is option D.
78. A system of masses rotating in different parallel planes is in dynamic balance if the
resultance force is equal to zero
resultant couple is equal to zero
resultant force and resultant couple are both equal to zero
resultant force is num
✅ The correct answer is option C.
79. The stroke of an engine is the
volume of the cylinder
length of the connecting rod
internal diameter of the cylinder
distance between T.D.C
✅ The correct answer is option D.
80. In petrol engines, the delay period is of the order of
0.001 second
0.002 second
0.003 second
0.004 second
✅ The correct answer is option B.