Which of the following is correct?

• Evaporation of water causes an increase in disorder of the system

• Melting of ice causes a decrease in the randomness of the system

• Condensation of steam causes an increase in disorder of the system

• There is practically no change in the randomness of the system when water is evaporated

The amount of the heat released when 20 mL 0.5 M NaOH is mixed with 100 ml 0.1 M HCl is x kJ. The heat of neutralisation is:

• - 100 x kJ/mol

• - 50 x kJ/mol

• + 100 x kJ/mol

• + 50 x kJ/mol

393.

For a spontaneous process, the correct statement(s) is (are)

• ($∆$G_system)_T, p > 0

• ($∆$S_system) + ($∆$S_surroundings) > 0

• ($∆$G_system)_T, p < 0

• ($∆$U_system)_t, v > 0

The second law of thermodynamic says that in a cyclic process

• work cannot be converted into heat

• heat cannot be converted into work

• work cannot be completely converted into heat

• heat cannot be completely converted into work

Equal volumes of molar hydrochloric acid 'and sulphuric acid are neutralized by dilute NaOH solution and x kcal and y kcal of heat are liberated respectively. Which of the following is true ?

• x = y

• x =y/2

• x = 2y

• none of these

Which of the following thermodynamic relation is correct ?

• dG = Vdp- SdT

• dE = pdV + TdS

• dH = -Vdp + Tds

• dG = Vdp + SdT

Calculate K_c for the reversible process given below if K_p = 167 and T = 800°C

CaCO₃ (s) $\rightleftharpoons$ CaO (s) + CO₂ (g)

• 1.95

• 1.85

• 1.89

• 1.60

For which reaction change of entropy will be positive?

• H₂(g) + I₂(g) $\rightleftharpoons$ 2HI (g)

• HCl (g) + NH₃ (g) $\rightleftharpoons$ NH₄Cl (s)

• NH₄NO₃ (s) $\rightleftharpoons$ N₂O (g) + 2H₂O (g)

• MgO(s) + H₂(g) $\rightleftharpoons$ Mg(s) + H₂O(l)

The product p of the nuclear reaction

${}_{92}{}^{235}\mathrm{U} + {}_0{}^1\mathrm{n} \to \mathrm{p} + {}_{36}{}^{92}\mathrm{Kr} + 3{}_0{}^1\mathrm{n}$, is

• ${}_{56}{}^{141}\mathrm{Sr}$

• ${}_{56}{}^{141}\mathrm{La}$

• ${}_{56}{}^{141}\mathrm{Ba}$

• ${}_{56}{}^{141}\mathrm{Cs}$

Which is correct for an enothermic reaction?

• $∆$H is positive

• $∆$H is negative

• $∆$E is negative

• $∆$H= zero