A polymer is termed as an ‘elastomer’, if its percentage elongation is more than 100%. An elastomer is termed as ‘rubber’ if its percentage elongation is more than _______________ percent ?
(A) 150
(B) 200
(C) 300
(D) 400
The units of the rate constant for a second order reaction are__________________?
(A) Sec-1. mole°
(B) Moles1. sec-1
(C) Moles-1. sec1
(D) Moles1. sec1
Between 230 and 370°C, blue brittleness is caused in mild steel because of the_________________?
(A) Immobility of dislocation
(B) Strain-ageing
(C) Increase in Young’s modulus
(D) Strain hardening
Principal alloying element in Elinvar (used for making hair springs for watches) is__________________?
(A) Copper
(B) Aluminium
(C) Nickel
(D) Zinc
An atom bomb works on the principle of __________________?
(A) Nuclear fission
(B) Nuclear fusion
(C) Both the nuclear fission & fusion
(D) Ionisation
A psychrometer does not measure the __________________ temperature of moist air?
(A) Dew point
(B) Dry bulb
(C) Wet bulb
(D) None of these
With increase in ___________________ Knocking tendency in a spark ignition petrol engine decreases?
(A) Supercharging
(B) Wall temperature
(C) Compression ratio
(D) Engine speed
Case hardening is not done by________________?
(A) Nitriding
(B) Hot dipping
(C) Electroplating
(D) Both ‘B’ & ‘C’
Oxide layer formed on the non-ferrous metal surface after its annealing is__________________?
(A) Removed by acid pickling
(B) Hammered into the surface
(C) Removed with coarse emery cloth
(D) Left as such to protect the surface