451. Dry saturated steam can be converted into super heated steam by____________________?
A. Forcing it downwards through a vertical tube
B. Passing it through a pressure reducing valve
C. Increasing its cross-sectional area of flow
D. None of these

452. Which of the following emissions in the exhaust gas of an I.C. engine causes the formation of photochemical smog ?
A. Hydrocarbons
B. Nitrogen oxides
C. Both A. & B.
D. Carbon monoxide

453. Enzymes belong to the category of_____________________?
A. Proteins
B. Vitamins
C. Carbohydrates
D. Fats

454. Which of the following is the most prone to atmospheric corrosion ?
A. Silver
B. Iron
C. Tin
D. Copper

455. Steel will respond to hardening by heat treatment processes, only when the minimum carbon content in it is _____________ percent?
A. 0.02
B. 0.2
C. 0.35
D. 0.5

456. _____________ iron is produced, when molten pig iron is chilled suddenly?
A. White cast
B. Grey cast
C. Wrought
D. None of these

457. Tin coating on metals is not done by_____________________?
A. Spraying
B. Powder metallurgy
C. Hot dipping
D. Electro-deposition

458. Metalloid is_______________________?
A. An element, which exhibits the properties of both metal & non metal
B. Highly electronegative in nature
C. An alloy
D. All A., B. & C.

459. Gun metal is an alloy of_________________________?
A. Nickel, tin and copper
B. Copper, tin and zinc
C. Copper, phosphorus and nickel
D. Manganese, phosphorus and nickel

460. Polymorphism is not exhibited by______________________?
A. Carbon
B. Iron
C. Phosphorous
D. None of these

NOTE
IF YOU THINK ANY OF THE MCQ ABOVE IS WRONG.
PLEASE COMMENT WITH CORRECT ANSWER AND ITS DETAIL EXPLANATION IN COMMENT BOX.
THANK YOU