Jet aircrafts fly at altitudes above 30,000 ft where the air is very cold at – 40ºC and the pressure is 0.28 atm.
The cabin is maintained at 1 atm pressure by means of a compressor which exchanges air from outside
adiabatically. In order to have a comfortable cabin temperature of 25ºC, we will require in addition -
(A) a heater to warm the air injected into the cabin
(B) an air-conditioner to cool the air injected into the cabin
(C) neither a heater nor an air-conditioner ; the compressor is sufficient
(D) alternatively heating and cooling in the two halves of the compressor cycle
Two rods, one made of copper and the other steel of the same length and cross sectional area are joined
together. (The thermal conductivity of copper is 385 J.s–1 .m–1. K–1 and steel is 50 J.s–1.m–1.K–1.) If the copper
end is held at 100ºC and the steel end is held at 0ºC, what is the junction temperature (assuming no other heat
losses) ?
(A) 12ºC (B) 50ºC (C) 73ºC (D) 88ºC
Insects constitute the largest animal group on earth. About 25-30% of the insect species are known to be
herbivores. In spite of such huge herbivore pressure, globally, green plants have persisted. one possible reason for
this persistence is –
(A) Food preference of insects has tended to change with time
(B) Herbivore insects have become inefficient feeders of green plants
(C) Herbivore population has been kept in control by predators
(D) Decline in reproduction of herbivores with time
When a person beings to fast, after some time glycongen stored in the liver is mobilized as a source of glucose.
Which of the following graphs best represents the change of glucose level (y axis) in his blood, starting from the
time (x -axis) when the beings to fast
Which one of the following is true about enzyme catalysis ?
(A) The enzyme changes at the end of the reaction
(B) The activation barrier of the process is lower in the presence of an enzyme
(C) The rate of the reaction is retarded in the presence of an enzyme
(D) The rate of the reaction is independent of substrate concentration
In cattle, the coat colour red and white are two dominant traits, which express equally F1 to produce roan ( red and
white colour in equal proportion). If F1 progeny are selfbred, the resulting progency in F2 will have phenotypic
ration (red : roan: white) is –
(A) 1: 1:1 (B) 3 : 9 : 3 (C) 1 : 2 : 1 (D) 3 : 9 : 4
Persons suffering from hypertension (high blood pressure) are advised a low-salt diet because–
(A) More salt is absorbed in the body of a patient with hypertension
(B) High salt leads to water retention in the blood that further increases the blood pressure
(C) High salt increases nerve conduction and increases blood pressure
(D) High salt causes adrenaline release that increases blood pressure
Three moles of an ideal gas expands reversibly under isothermal condition form 2 L to 20 L at 300 K. The amount
of heat-change (in kJ/mol) in the process is –
(A) 0 (B) 7.2 (C) 10.2 (D) 17.2
The ΔH for vaporization of a liquid is 20 kJ/mol. Assuming ideal behaviour, the change in internal energy for the
vaporization of 1 mol of the liquid at 60°C and 1 bar is close to –
(A) 13.2 kJ/mol (B) 17.2 kJ/mol (C) 19.5 kJ/mol (D) 20.0 kJ/mol