19,000+ solved questions for JEE Advanced, JEE Mains, NEET & IChO — with answers and expert explanations.
One mole of an ideal gas expands reversibly and adiabatically from a temperature of 27°C. If the work done during the process is 3 kJ, then final temperature of the gas is:(CV = 20 J/K)
Which of the following expressions regarding entropy is not correct? (a) system q S T (b) system total surrounding S S S (c) final initial S S S (d) total system surrounding S S S
Read the following statements regarding spontaneity of a process and mark the appropriate choice. (i) When enthalpy factor is absent then randomness factor decides spontaneity of a process. (ii) When randomness fact…
Unit of entropy is
In which case change in entropy is negative?
When one mole of an ideal gas is compressed to half of its initial volume and simultaneously heated to twice its initial temperature, the change in entropy of gas (∆S) is :
One mole of an ideal diatomic gas (Cv = 5 cal) was transformed from initial 25°C and 1 L to the state when temperature is 100°C and volume 10 L. The entropy change of the process can be expressed as (R = 2 calories/mo…
Pick out the wrong statement
Which one of the following is correct? (a) G H T S
G is the net energy available to do useful work and is a measure of free energy. If a reaction has positive enthalpy change and positive entropy change, under what conditions will the reaction be spontaneous?
2 moles of ideal gas at 27°C temperature is expanded reversibly from 2 lit. to 20 lit. find entropy change. (R = 2 cal/mol K)
Which of the following reactions define o f G ? (a) diamond C O g CO g → (b) H g F g HF g → (c) H P O H O 2H PO → (d) SO g O g SO g →
H and E for the reaction, Fe O s 3H g 2Fe s H O l → at constant temperature are related as (a) H E (b) H E RT (c) H E RT (d) H E 3RT
The following data is known about the melting of a compound AB. ∆H = 9.2 kJ mol–1. ∆S = 0.008 kJ K–1mol–1. Its melting point is :
The densities of graphite and diamond at 298 K are 2.25 and 3.31 g cm–3, respectively. If the standard free energy difference is equal to 1895 J mol–1, the pressure at which graphite will be transformed into diamond a…
When 0.5 g of sulphur is burnt to SO₂ 4.6 kJ of heat is liberated. What is the enthalpy of formation of sulphurdioxide?
The heat of formation of Fe O s is –824.2 kJ mol–1. ∆H for the reaction. 2Fe O s 4Fe s 3O g → is:
H for the reaction, C(graphite) 2H (g) CH (g) → at 298 K and 1 atm is – 17900 cal. The E for the above conversion would be
The standard enthalpies of formation of HCl(g), H (g) and Cl₂(g) are –92.2, 217.7 and 121.4 kJ mol-1 respectively. The bond dissociation energy of HCl is:
A reaction occurs spontaneously if (2005)
Assume each reaction is carried out in an open container. For which reaction will H = E ? (CBSE AIPMT 2006) (a) H (g) Br (g) 2HBr(g) → (b) C(s) 2H O(g) 2H (g) CO (g) → (c) PCl (g) PCl (g) Cl (g) → (d) 2CO(g) O (g) 2CO…
The enthalpy and entropy change for the reaction: 2(l) 2(g) (g) Br Cl 2BrCl → are 30 kJ mol–1 and 105JK–1 mol–1 respectively. The temperature at which the reaction will be in equilibrium is (2006)
Consider the following reaction –1 (aq) (aq) (l) –1 2(g) 2(g) (l) 2(g) 2(g) (g) (l) –1 2(g) 2(g) 2(g) (l) –1 (i)H OH H O , H X kJ mol (ii)H 1/ 2O H O , H X kJ mol (iii)CO H CO H O , H X kJ mol (iv)C H 5 / 2O 2CO H O ,…
Bond dissociation enthalpy of H₂ Cl₂, and HCl are 434, 242 and 431 kJ mol respectively. Enthalpy of formation of HCl is (2008)
A system undergoes a 2-step process. In step 1, 15 J of work is done on the system as its internal energy increases by a total of 30 J. In step 2, at constant volume, the system decreases its internal energy by 20 J. …