NEET Practice Questions (MCQs) with Answers & Solutions

In conversion of lime–stone to lime, $ CaCO_3(s) \rightarrow CaO(s) + CO_2(g) $ the values of $OH ^\circ $ and $ OS ^\circ $ are $ +179.1 kJ mol ^ {–1} $ and 160.2 J/K respectively at 298 K and 1 bar. Assuming that $OH ^\circ $ and $OS ^ \circ $ do not change with temperature, temperature above which conversion of limestone to lime will be spontaneous is :

For a reversible process at T = 300 K, the volume is increased from $ V_i = 1 L to V_f = 10 L$ . Calculate H if the process is isothermal

Assuming that water vapour is an ideal gas, the internal energy change (OU) when 1 mol of water is vapourisedat 1 bar pressure and $ 100 ^\circ C $ , (Given : Molar enthalpy of vapourization of water at 1 bar and $ 373 K = 41 kJ mol ^ {–1} and R = 8.3 J mol ^ {–1} K ^{–1}) $ will be :

The standard enthalpy of formation $ (OHf ^ \circ ) $ at 398 K for methane, $ CH_4(g) is 74.8 kJ mol ^ {–1} $ . The additional information required to determine the average energy for C – H bond formation would be.

Standard entropy of $X_2, Y_2 and XY_3$ are $60, 40 and 50 JK^{–1} mol^{–1}$ , respectively. For the reaction,$ 1/2 X_2 + 3/2 Y_2 \rightarrow XY_3 OH = – 30 kJ $ . To be at equilibrium the temperature will be :

On the basis of the following thermochemical data : $ (O_ƒG ^\circ H ^+_{(aq)} = 0) $ $H_2O(l) \rightarrow H+ (aq) + OH^– (aq.) ; \triangle H = 57.32 kJ $ $ H_2(g) + O_2(g) \rightarrow H_2O( l); \triangle H = – 286.20 kJ $ The value of enthalpy of formation of $OH^ - ion at 25 ^\circ C $ is :

In a fuel cell methanol is used as fuel and oxygen gas is used as an oxidizer. The reaction is $CH_3OH(l) + 3/2O2 (g) \rightarrow CO_2(g) + 2H_2O(l) $ . At 298 K, standard Gibb’s energies of formation for $ CH_3OH(l), H_2O(l) and CO_2 (g) are –166.2,–237.2 and –394.4 kJ mol^{–1} $ respectively. If standard enthalpy of combustion of methanol is $ –726kJ mol ^ {–1} $ , efficiency of the fuel cell will be :

The standard enthalpy of formation of $ NH_3 is – 46.0 kJ mol^{–1} $ . If the enthalpy of formation of $H_2$ from its atoms is $ –436 kJ mol^{–1} $ and that of $ N_2 is –712 kJ mol^{–1} $ , the average bond enthalpy of N – H bond in $NH_3$ is

Choose the correct option about the following sentnences [T= True , F =False]

(i) Ice in contact with water constitutes a homogeneous system.

(ii) The process is known as isochoric in which the pressure remains constant throughout the change, i.e., dP = 0.

(iii) A spontaneous process is reversible in nature.

(iv) In an isolated system, one form of energy cannot be converted into another, i.e., internal energy remains constant.

Choose the correct option about the following sentnences [T= True , F =False] (i)Molar heat capacity at constant pressure = Molar heat capacity at constant volume + POV. (ii)A spontaneous process is accompanied by a decrease in entropy. (iii) $ \triangle Hsub = \triangle Hfusion + \triangle Hvap $ . (iv)The standard heat of formation represents the formation of the compound from its elements at $ 25 ^\circ C $ and one atmospheric pressure. (v)Whenever an acid is neutralised by a base, the net reaction is