Mechanical Operations - Practice Test

[#186] Height of liquid in agitation tank is normally maintained equal to the tank diameter. However, if the tank is too tall and a large liquid hold up is desired, then two or more impellers mounted on the same shaft may be used. The clearance between the tank bottom and the bottom most impeller should be about (where, D = impeller diameter)

(A) 0.5 D

(B) D

(C) 1.5 D

(D) 2 D

(E) 0.5 D

(F) D

(G) 1.5 D

(H) 2 D

Correct Answer

(B) D
(F) D

[#187] Washability curve based on float and sink test enables an assessment to be made of the possibility of cleaning a coal fraction based on the

(A) Density separation

(B) Differential wettability

(C) Size

(D) Volatile matter content

Correct Answer

(A) Density separation

[#188] Which of the following is the most suitable for handling fibrous and dense slurries?

(A) Propeller agitator

(B) Cone type agitator

(C) Turbine agitator

(D) Radial propeller agitator

Correct Answer

(B) Cone type agitator

[#189] For efficient grinding, ball mills must be operated

(A) At a speed less than the critical speed

(B) At a speed more than the critical speed

(C) At a speed equal to the critical speed

(D) With minimum possible small balls

Correct Answer

(A) At a speed less than the critical speed

[#190] Rittinger's crushing law states that

(A) Work required to form a particle of any size is proportional to the square of the surface to volume ratio of the product

(B) Work required to form a particle of a particular size is proportional to the square root of the surface to volume ratio of the product

(C) Work required in crushing is proportional to the new surface created

(D) For a given machine and feed, crushing efficiency is dependent on the size of the feed & product

Correct Answer

(C) Work required in crushing is proportional to the new surface created

Mechanical Operations - Study Mode

Correct Answer

[#187] Washability curve based on float and sink test enables an assessment to be made of the possibility of cleaning a coal fraction based on the

Correct Answer

[#188] Which of the following is the most suitable for handling fibrous and dense slurries?

Correct Answer

[#189] For efficient grinding, ball mills must be operated

Correct Answer

[#190] Rittinger's crushing law states that

Correct Answer