Thermal Propert...

Choose the correct alternative: 
Water expands on reducing its temperature below _______ $$^{\circ} C $$ .

The temperature of the two outer surfaces of a composite slab, consisting of two materials having coefficients of thermal conductivity $$K$$ and $$2K$$ and thickness $$x$$ and $$4x$$ respectively are $$T_{2}$$ and $$T_{1}$$ ($$T_{2} > T_{1}$$). The rate of heat transfer through the slab in a steady state is $$\displaystyle \left [\frac{A(T_{2}-T_{1})K}{x} \right ]f$$, where $$f$$ equals to :

One end of a thermally insulated rod is kept at a temperature $$T_{1}$$  and the other at $$T_{2}$$. The rod is composed of two sections of lengths $$l_{1}$$  and  $$ l_{2}$$ and thermal conductivities $$K_{1} $$ and $$ K_{2}$$ respectively. The temperature at the interface of two sections is :

A closed container of volume 0.02 m$$^3$$ contains a mixture of neon and argon gases at a temperature of 27$$^{0}$$ C and at a pressure of $$1\times 10^{5}N/m^{2}$$. The total mass of the mixture is 28 g. If the gram molecular weights of neon and argon are 20 and 40 respectively, the masses of the individual gases in the container are respectively(assuming them to be ideal) [R = 8.314 J/mol K]

A 90 cm long barometer tube contains some air above the mercury. The reading is 74.5 cm when the true pressure is 76 cm at the temperature $$15^{0} C$$. If the reading is observed to be 75.8 cm on a day when the temperature is $$5^{0}C$$, then the true pressure is:

A smooth vertical tube with two different cross-sections is open at both ends. They are fitted with  pistons of different areas of cross- section and each  piston moves within a particular section. One mole of a gas enclosed between the pistons which are tied with non-stretchable threads. The difference  in cross-sectional area of  pistons $$10\mathrm{c}\mathrm{m}^{2}$$ The mass of gas confined between  pistons is  5kg. The outside  pressure is 1 atmosphere$$=10^{5}N/m^{2}$$. By how many degrees must the gas between pistons be heated to shift the piston by 5 cm?

A horizontal uniform glass tube of 100cm length is sealed at both ends contains 10 cm mercury column in the middle the temperature and pressure of air on either side of mercury column are respectively 31$$^{0}$$C and 76cm of mercury if the air column at one end is kept at 0$$^{0}$$C and the other end at 273$$^{0}$$C the pressure of air which is at 0$$^{0}$$C is (in cm of Hg )

A closed hollow insulated cylinder is filled with gas at 0$$^{0}$$C and also contains an insulated piston of negligible weight and negligible thickness at the the middle point. The gas at one side of the piston is heated to 100$$^{0}$$C . If the piston moves 5cm, the length of the hollow cylinder is

Two identical containers each of volume V$$_{0}$$ are joined by a small pipe. The containers contain identical gases at temperature T$$_{0}$$ and pressure P$$_{0}$$. One container is heated to temperature 2T$$_{0}$$ while maintaining the other at the same temperature. The common pressure of the gas is P and n is the number of moles of gas in container at temperature 2T$$_{0}$$.

Heat energy always flows from a body at low temperature to a body at high temperrature