247. Heat transfer to the water wall in a high pressure water wall type boiler furnace is mainly by
A. Conduction
B. Convection
C. Both A & B
D. Radiation
✅ The correct answer is option D.
250. A machine having assumed life of 20 years is purchased for Rs 32000/-. Its scrap value at the end of its life is Rs 8000/-. If the depreciation is calculated by diminishing balance method, then percentage reduction in its value at the end of first year is __________ percent.
A. 6.7
B. 7.6
C. 10.3
D. 15.2
✅ The correct answer is option A.
253. The reductant used in the extraction of magnesium from calcined dolomite via Pidgeon’s process is
A. Pure carbon
B. Pure silicon
C. Ferro silicon
D. Ferro manganese
✅ The correct answer is option C.
256. __________ property of steel increases by addition of large amount of silicon in it.
A. Mechanical
B. Machining
C. Magnetic
D. Refractory
✅ The correct answer is option C.
224. Tesla metre per ampere (T. m/A) is the unit for the measurement of
A. Magnetic succeptibility
B. Magnetic moment
C. Permeability of free space
D. Flux density
✅ The correct answer is option C.
227. Gross national product (GNP) means the total value of __________ in a country.
A. Goods produced
B. Gold reserve
C. Earning of the citizens
D. Taxes paid
✅ The correct answer is option A.
190. Corona discharge is related to the operation of a/an
A. Induction motor
B. Electrostatic precipitator
C. Fast breeder reactor
D. Magneto hydrodynamic generator (MHD)
✅ The correct answer is option B.
193. Steam condenser tubes are made of ad-mirability brass, in which percentage of zinc & copper are __________ respectively.
A. 70 & 30
B. 30 & 70
C. 50 & 50
D. 90 & 10
✅ The correct answer is option A.
196. An example of unsteady non uniform flow is the flow of liquid under pressure through a
A. Tapering pipe at constant flow rate
B. Tapering pipe at either decreasing or increasing flow rate
C. Long pipeline of constant diameter
D. None of these
✅ The correct answer is option B.
199. The minimum carbon content in steel should be __________ percent for it to respond to a hardening treatment.
A. 0.2
B. 0.4
C. 0.6
D. 0.8
✅ The correct answer is option A.