⚙️ Mechanical Eng Solved MCQs with Answers

Practice 934 approved ⚙️ Mechanical Eng questions with verified answers from the 🛠️ Engineering Essentials subject for Pakistan exams.

934 solved MCQs

Malleable cast iron is producedAnswer: from white cast iron by annealing process Smelting is the process ofAnswer: reducing the ore with carbon in the presence of a flux The percentage of carbon in cast iron varies fromAnswer: 1.7 to 4.5 The ability of a material to absorb energy in the plastic range is calledAnswer: toughness Brass is an alloy ofAnswer: copper and zinc A material is said to be allotropic, if it hasAnswer: different crystal structures at different temperatures U₂₃₃ is producedAnswer: when thorium is irradiated by neutrons Closed packed hexagonal space lattice is found inAnswer: zinc, magnesium, cobalt, cadmium, antimony and bismuth The hardness and tensile strength in austenitic stainless steel can be increased byAnswer: hardening and cold working The pressure at the end of compression, in diesel engines, is approximatelyAnswer: 35 bar The quenching of steel from the upper critical point results in a fine grained structure.Answer: Agree The detonation is also called knocking or pinking.Answer: Yes An alloy steel which is work hardenable and which is used to make the blades of bulldozers, bucket wheel excavators and other earth moving equipment contain iron, carbon andAnswer: manganese The pre-ignition occurs before the spark is produced whereas detonation develops after the introduction of spark.Answer: Agree Which of the following has a fine gold colour and is used for imitation jewellery?Answer: Aluminium bronze The energy released during the fission of one atom of Uranium - 235 in million electron volts is aboutAnswer: 200 Morse test can be conducted forAnswer: multi-cylinder engines When the steel is normalised, itsAnswer: all of these White cast iron has a high tensile strength and a low compressive strength.Answer: No In a four stroke cycle petrol engine, the charge is compressed when both the valves (i.e. inlet valve and exit valve) are closed,Answer: Agree Dye penetrant method is generally used to locateAnswer: surface defects The charge is fed into the blast furnace through theAnswer: throat The thermal efficiency of diesel engines on weak mixtures isAnswer: higher A small percentage of boron is added to steel in order toAnswer: increase hardenability The injection pressure in a diesel engine is aboutAnswer: 100 bar Which of the following process of steel making is in operation at Tata Iron and Steel Works, Jamshedpur?Answer: Duplex process High speed compression engines operate onAnswer: Dual-combustion cycle The unit cellsAnswer: all of the above In a four stroke cycle petrol engine, the inlet valveAnswer: opens at 20° before top dead centre and closes at 40° after bottom dead centre Tungsten when added to steel __________ the critical temperature.Answer: raises