Which among the following statements about open, closed, and isolated systems is correct?

1.	The presence of reacting species in a covered beaker represents an open system.
2.	In a closed system, there is an exchange of both energy and matter between the system and its surroundings.
3.	A system containing reactants in a closed vessel made of copper is an example of a closed system.
4.	A system containing reactants in a thermos flask or any other closed, insulated vessel is an example of a closed system.

What happens to the specific heat of a gas when its volume is reduced to half of its initial value?

During the complete combustion of one mole of butane, 2658 kJ of heat is released. The thermochemical reaction for this change is:

Calculate the correct values of heat transfer (q), change in temperature (ΔT), and work done (W) for the free expansion of an ideal gas under adiabatic conditions.
1.  q = 0, ΔT ≠ 0, W = 0
2.  q ≠ 0, ΔT = 0, W = 0
3.  q = 0, ΔT = 0, W = 0
4.  q = 0, ΔT = 0, W ≠ 0

The pressure-volume work for an ideal gas can be calculated by using the expression $\mathrm{W}={\int }_{{\mathrm{V}}_{\mathrm{i}}}^{{\mathrm{V}}_{\mathrm{f}}}{\mathrm{p}}_{\mathrm{ext}}d\mathrm{V}$.

The work can also be calculated from the pV-plot by using the area under the curve within the specified limits.
An ideal gas is compressed (a) reversibly or (b) irreversibly from volume ${\mathrm{V}}_{\mathrm{i}}$ to ${\mathrm{V}}_{\mathrm{f}}$.
The correct option is:

1. $\mathrm{W}<mspace\; width="1em"></mspace>\left(\mathrm{reversible}\right)=\mathrm{W}<mspace\; width="1em"></mspace>\left(\mathrm{irreversible}\right)$

2. $\mathrm{W}<mspace\; width="1em"></mspace>\left(\mathrm{reversible}\right)<\mathrm{W}\hspace{0.17em}\left(\mathrm{irreversible}\right)$

3. $\mathrm{W}<mspace\; width="1em"></mspace>(\mathrm{reversible})\; >\mathrm{W}<mspace\; width="1em"></mspace>(\mathrm{irreversible})$

4. $\mathrm{W}<mspace\; width="1em"></mspace>\left(\mathrm{reversible}\right)=\mathrm{W}<mspace\; width="1em"></mspace>\left(\mathrm{irreversible}\right)+{\mathrm{p}}_{\mathrm{ext}}.∆\mathrm{V}$

The entropy change can be calculated by using the expression $∆\mathrm{S}=\frac{{\mathrm{q}}_{\mathrm{rev}}}{\mathrm{T}}$. When water freezes in a glass beaker, the correct statement among the following is:

Which of the following algebraic relationships is correct based on the given thermochemical equations?

1. z = x + y

2. x = y + z

3. x = y - z

4. y = 2z - x

Based on the reactions, ascertain the valid algebraic relationship:
$\left(i\right)$ $C\left(g\right)$ $+4H$ $\left(g\right)$ $\to C{H}_4\left(g\right);$ $$
$∆H_r$ $=x$ $kJ$ $mo{l}^{-1}$
$\left(ii\right)$ $C\left(graphite\right)$ $+$ $2H_2$ $\left(g\right)$ $\to$ $$ $C{H}_4;$ $$
$∆H_r$ $$ $=$ $y$ $kJ$ $mo{l}^{-1}$

The enthalpies of elements in their standard states are taken as zero. The enthalpy of formation of a compound is :