What is the change in internal energy for 5 moles of an ideal gas when it undergoes reversible compression from 100 K to 200 K? 
(Given C_V = 28 J K^–1 mol^–1)​​​​​​

1.	ΔU = 8kJ	2.	ΔU = 14kJ
3.	ΔU = 10kJ	4.	ΔU = 2.8 kJ

The incorrect statement(s) among the following statements is/are -

1. (i), (iv)
2. (ii), (iv)
3. (iii), (iv)
4. (i), (iii)

The average S–F bond energy in kJ mol^–1 of SF₆ is:

 [The values of standard enthalpy of formation of
SF₆(g), S(g), and F(g) are –1100, 275, and 80 kJmol^–1 respectively.]

In an exothermic reaction, heat is evolved, and the system loses heat to the surrounding. The correct choice among the following for such a system are-

(a) q_p will be negative

(b) ${∆}_{\mathrm{r}}\mathrm{H}$ will be negative

(c) q_p will be positive

(d) ${∆}_{\mathrm{r}}\mathrm{H}$ will be positive

1. (a, b)

2. (b, c)

3. (c, d)

4. (a, d)

Consider a cycle followed by an engine (figure). 

1 to 2 is isothermal,
2 to 3 is adiabatic,
3 to 1 is adiabatic.
Such a process does not exist, because:

Choose the correct alternatives:

The entropy change for the melting of 'x' moles of ice at 273 K and 1 atm pressure is 28.80 cal K^–1.
The value of 'x' is:
(Given: heat of fusion is 80 cal g^–1)