$Assertion :$ When a glass of hot milk is placed in a room and allowed to cool,its entropy decreases.
$Reason :$ Allowing a hot object to cool does not violate the second law of thermodynamics.

$N_{2}$ gas is heated from $300\, K$ to $600\, K$ through an isobaric process. Find the change in entropy of the gas. $(n = 1\, \text{mole})$ (in $J/K$)

The graphs below show the entropy versus energy $U$ of two systems $1$ and $2$ at constant volume. The initial energies of the systems are indicated by $U_{1, i}$ and $U_{2, i}$,respectively. The graphs are drawn to the same scale. The systems are then brought into thermal contact with each other. Assume that,at all times,the combined energy of the two systems remains constant. Choose the most appropriate option indicating the energies of the two systems and the total entropy after they achieve equilibrium.

$A$ solid body of constant heat capacity $1\,J/^{\circ}C$ is being heated by keeping it in contact with reservoirs in two ways:
$(i)$ Sequentially keeping in contact with $2$ reservoirs such that each reservoir supplies the same amount of heat.
$(ii)$ Sequentially keeping in contact with $8$ reservoirs such that each reservoir supplies the same amount of heat.
In both cases, the body is brought from an initial temperature $100^{\circ}C$ to a final temperature $200^{\circ}C$. The entropy change of the body in the two cases respectively is:

Entropy of a system decreases .........

One mole of an ideal gas at $300 \ K$ in thermal contact with surroundings expands isothermally from $1.0 \ L$ to $2.0 \ L$ against a constant external pressure of $3.0 \ atm$. In this process,the change in entropy of the surroundings $(\Delta S_{\text{surr}})$ in $J \ K^{-1}$ is $(1 \ L \ atm = 101.3 \ J)$.