271. Spherical shape of mercury droplets is due to its____________________?
A. High viscosity
B. Low surface tension
C. High density
D. High surface tension

272. Carbon is present in the form of _______________________ in grey cast iron ?
A. Spheroids
B. Nodular aggregates of graphite
C. Flakes
D. Cementite

273. The heat of neutralisation remains constant, when there is a reaction between dilute solutions of strong _____________________?
A. Base and strong acid
B. Base and weak acid
C. Acid and weak base
D. None of these

274. ‘Cryogenics’ is concerned with the generation & use of low temperature in the range of____________________?
A. 0°K to 123°K
B. 0°C to – 123°C
C. 0°C to – 273°C
D. 0°K to 273°K

275. __________________ of air does not increase with increase in temperature?
A. Density
B. Thermal diffusivity
C. Viscosity
D. Thermal conductivity

276. The value of y = cp/cv. at < 500°C for air & most common gases can be safely assumed to be_____________________?
A. 0.8
B. 1
C. 1.4
D. 1.8

277. Which of the following varies as the square root of oil pressure during atomisation of fuel oil through a pressure jet burner ?
A. Output & fineness
B. Velocity
C. Both A. & B.
D. None of these

278. ______________ joint is usually used for joining cast iron pipes mostly used for temporary pipelines, where it may be necessary to dismantle & reassemble the pipeline very frequently ?
A. Collar
B. Flanged
C. Bell and Spigot
D. Expansion

279. The pressure outside a bubble/droplet of liquid is ________________ the internal pressure?
A. Greater than
B. Less than
C. Equal to
D. Unpredictable; depends on the bubble size

280. Alumina, silica, lime and iron oxide are the basic raw material for the manufacture of Portland cement. The component of Portland cement which first hardens is_____________________?
A. 5CaO. 3 Al2O3
B. 3CaO. Al2O3
C. 3CaO. SiO2
D. 2CaO. SiO2

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