113. Which of the following is an ore dressing operation?
A. Classification
B. Smelting
C. Roasting
D. None of these
✅ The correct answer is option A.
116. Electrometallurgy is not involved in the extraction of __________ from its ore.
A. Aluminium
B. Tin
C. Lead
D. Both B & C
✅ The correct answer is option D.
119. Diamond does not conduct electricity, because
A. Its structure is very compact
B. No free electrons are present
C. It is of crystalline nature
D. There are only carbon atoms present
✅ The correct answer is option B.
122. Filler metal is not used in the __________ welding.
A. Seam
B. Electric spot
C. Projection
D. All of the above
✅ The correct answer is option D.
125. Use of flux during soldering is done to
A. Increase flidity of solder by lowering its melting temperature
B. Prevent oxide formation
C. Wash away surplus solder
D. Full up the joint gap
✅ The correct answer is option B.
128. Pick out the wrong statement about the machinability of metals. Machinability of a metal
A. Decreases with increase in strain hardening tendencies
B. Decreases with increase in hardness, in general
C. Depends on the composition, microstructure and physical & mechanical properties
D. Decreases with increases in tensile strength & decrease in grain size
✅ The correct answer is option D.
131. Drossing is a __________ operation.
A. Smelting
B. Dressing
C. Roasting
D. Dressing
✅ The correct answer is option C.
133. The boiling & freezing points on a newly defined temperature scale in degree ‘D’ are 400°D & 100°D respectively. The temperature reading corresponding to 60°C on this new temperature scale will be equal to __________ °D.
A. 140
B. 180
C. 240
D. 280
✅ The correct answer is option D.
135. Refrigerative cooling employed during long distance transportation of food stuffs is normally done by
A. Ice
B. Liquid nitrogen
C. Liquid oxygen
D. Vacuum evaporation
✅ The correct answer is option B.
137. Hoope’s cell is predominantly used for the electrolytic refining of
A. Zinc
B. Copper
C. Aluminium
D. Tin
✅ The correct answer is option C.