hello I am stuck in some engineering questions could you please take a look?

Cocks rather than valves are usually fitted for boiler water gauge glass mountings because:
(a) they can be shut off more quickly should the gauge glass break.
(b) they are easier to make and hence cheaper.
(c) they are easier to maintain and repair.
(d) they are required by Transport Canada Regulations.


The main disadvantage of a submerged-coil type of evaporator is:
(a) high steam consumption per kilogram of water evaporated.
(b) high cleaning costs.
(c) poor performance.
(d) all of the disadvantages listed above.


prolonged idling causes:
1. carbon build-up
2. overheating
3. increased LO consumption
4. smokey exhaust

( I think long idling causes incomplete combustion because idling isn't what engines aren't actually designed for. The incomplete combustion leads to carbon build up(soot) and smokey exhaust. what would be your answer?)

lube oil has to fulfill the functions of
1.cooling
2.lubricating
3.carrying away dirt and initial particles
4.working under various load conditions

(I think all the above are correct.)

I think Q1 = A, Q2 = A, Q3 = 1 ( i think your thoughts are rational), Q4 = 2 but yes, "all the above" would be better.

Thank you for your replay!