2) As compared to copper, the conductivity (both thermal and electrical) of aluminium is about

39%

49%

59%

69%

Correct Answer- (C)

1) As compared to steel, the density of aluminium is about

half

one-third

one-fourth

one-fifth

Correct Answer- (D)

3) What is produced when aluminium is oxidized by water?

Hydrogen

Oxygen

Nitrogen

Carbon dioxide

Correct Answer- (A)

4) Which of the following can penetrate the protective skin of aluminium and corrode the metal?

Acidic substances

Alkaline substances

Both (a) and (b)

Neither (a) nor (b)

Correct Answer- (B)

6) Which one of the following metals is most impervious to X-rays and gamma radiation?

Lead

Zinc

Gold

Tin

Correct Answer- (A)

7) The principal constituent of solder is

Zinc

Lead

Tin

Antimony

Correct Answer- (C)

8) Which one of the following is used in heat exchangers (radiators)?

Brass

Bronze

Duralumin

Phosphor bronze

Correct Answer- (A)

9) Which one of the following has suitable acoustic properties for use in musical instruments?

Bronze

Muntz metal

Gilding metal

Brass

Correct Answer- (D)

10) Galvanizing is providing a protective coating on mild steel of the metal

zinc

lead

tin

aluminium

Correct Answer- (A)

11) Which of the following metals is used in batteries?

zinc

lead

tin

copper

Correct Answer- (B)

12) Stainless steel contains chromium, minimum percentage

6.5%

10.5%

14.5%

18.5%

Correct Answer- (B)

13) Which type of stainless steel is used for making knives and turbine blades?

Duplex

Ferritic

Austenitic

Martensitic

Correct Answer- (D)

14. Two dissimilar metals are connected in a corrosive electrolytic environment. The type of corrosion likely to occur is

pitting corrosion

galvanic corrosion

Crevice corrosion

Graphitic corrosion

Correct Answer- (B)

15) Which one among the following metals is most corrosive?

Tin

Lead

Zinc

Magnesium

Correct Answer- (D)

16) Which one among the following metals is least corrosive?

Gold

Silver

Stainless steel

Aluminium

Correct Answer- (A)

17) Which one among the following is NOT considered “noble”?

Gold

Silver

Tin

Graphite

Correct Answer- (C)

18) In the process of calorising, which type of powder is used for protection against corrosion?

Aluminium powder

Zinc powder

Tin powder

Lead powder

Correct Answer- (A)

19. Which one of the following processes involves pressing or rolling sheets together under high pressure?

Calorising

Sherardising

Lacquering

Cladding

Correct Answer- (B)

20) In the process of sherardising, which type of powder is used to form a corrosion resistant coating?

Aluminium powder

Zinc powder

Tin powder

Lead powder

Correct Answer- (B)

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