At a given temperature the internal energy of a substance
A solid cube and a solid sphere of the same material have equal surface area. Both are at the same temperture 120°C ,then

Solution
Rate of cooling of a body R=\(\frac{\Delta \Theta }{t}=\frac{A\varepsilon \sigma (T^{4}T_{0}^{4})}{mc}\)
⇒R\(\alpha \frac{A}{m}\alpha \frac{Area}{Volume}\) [m=\(\rho\)]V
⇒For the same surface area. \(R\alpha \frac{1}{Volume}\)∵Volume of cube < Volume of sphere ⇒ R_{cube} > R_{sphere} i.e., cube, cools down with faster rate.
Which of the following is not close to a black body?
The sprinkling of water slightly reduces the temperature of a closed room because
The wavelength of radiation emitted by a body depends upon
The fastest mode of transfer of heat is
According to the kinetic theory of gases
There are four objects A,B,C and D. It is observed that A and B are in thermal equilibrium and C and D are also in thermal equilibrium. However, A and C are not in thermal equilibrium. We can conclude that –

Solution
Thermal equilibrium means same temperature.
By the first law of thermodynamics, for solids
5g ice at 0ºC is mixed with 5g of steam at 100ºC . What is the final temperature?

Solution
Heat required by ice to raise its temperature to 100ºC,
Q1= m1L1+ m1c1Δθ1 =5×80+5×1×100= 400+500=900 cal
Heat given by steam when condensed, Q2= m2L2 =5×536= 2680 calas Q2>Q1.
This means that whole steam is not even condensed. Hence temperature of mixture will remain at 100ºC.