List of top Chemistry Questions

The enthalpy change for a given reaction at 298 K is \( -x \, \text{J mol}^{-1} \). For the reaction to be spontaneous at 298 K, the entropy change at that temperature
A plot of \( \ln K \) against \( 1/T \) (abscissa) is expected to be a straight line with intercept on ordinate axis equal to
The wave number of the first emission line in the Balmer series of H-Spectrum is: \[ (R = \text{Rydberg constant}) \]
\( a \) moles of \( \text{PCl}_5 \) is heated in a closed container to equilibrate \[ \text{PCl}_5 (g) \rightleftharpoons \text{PCl}_3 (g) + \text{Cl}_2 (g) \] at a pressure of \( P \) atm. If \( x \) moles of \( \text{PCl}_5 \) dissociate at equilibrium, then the correct expression for the equilibrium constant is
In a reaction \( A \to \) Products, when start is made from \( 8.0 \times 10^{-2} \) M of A, half-life is found to be 120 minutes. For the initial concentration \( 4.0 \times 10^{-2} \) M, the half-life of the reaction becomes 240 minutes. The order of the reaction is:
A reaction \( A_2 + B \to \) Products, involves the following mechanism: \[ A_2 \rightleftharpoons 2A \text{ (fast)} \quad \text{(A being the intermediate)} \] \[ A + B \xrightarrow{k_2} \text{ Products (slow)}. \] The rate law consistent to this mechanism is:
\( \text{t-butyl} - \text{CH}_3 \text{C} - \text{CH}_2 \text{OH} \) can’t give decarboxylation while normally \( \alpha-\beta \) unsaturated acid give this reaction because
Standard entropy of X2, Y2 and X3Y is 60, 40 and 50 J K\(^{-1}\) mol\(^{-1}\), respectively. For the reaction, \[ 1/2 \, \text{X}_2 + 3/2 \, \text{Y}_2 \rightarrow \text{X}_3\text{Y}, \, \Delta H = -30 \, \text{kJ}, \, T = 1250 \, \text{K} \] the equilibrium temperature will be
If the reaction \( \text{N}_2 + 3\text{H}_2 \rightarrow 2\text{NH}_3 \) occurs at 200°C and 1000 atm then the graph showing the correct equilibrium yield at 400°C is
Group 15 elements have more electron gain enthalpy than group 16 elements. The correct reason for this is
Which type of carbocation is/are formed when \( \text{OH} \) is treated with an acid?
For hydrogen-oxygen fuel cell, the cell reaction is \[ 2\text{H}_2(g) + \text{O}_2(g) \rightarrow 2\text{H}_2\text{O}(l) \] If \( \Delta G^\circ (H_2O) = -237.2 \, \text{kJ mol}^{-1} \), then emf of this cell is
At 298 K, the conductivity of a saturated solution of AgCl in water is \( 2.6 \times 10^{-5} \, \text{S cm}^{-1} \). Its solubility product at 298 K is
The protein present in the hair is
Acetophenone and Benzophenone can be distinguished by which of the following test
Which one of the following show stereoisomerism?
One mole of an ideal gas at 300 K is expanded isothermally from an initial volume of 1 litre to 10 litres. Then \( \Delta S \) (cal deg\(^{-1}\) mol\(^{-1}\)) for this process is: \( R = 2 \, \text{cal K}^{-1} \text{mol}^{-1} \)
The product P in this reaction is \[ R - \text{NC} - \text{LiAlH}_4 \quad \longrightarrow \quad P \]
For a reaction A \( \rightarrow \) B; \( \Delta H = 20 \, \text{kJ mol}^{-1} \), the activation energy of the forward reaction is 85 kJ/mol. The activation energy of the backward reaction will be
By which reaction ketal is formed?
Which of the two acids form anhydrides? (I) Oxalic acid
(II) Succinic acid
(III) Benzoic acid
(IV) Phthalic acid
The correct order of electrophilic substitution for the compounds given above will be
For meso tartaric acid, the correct configuration for chiral carbon is
The correct set of quantum numbers for Rb (atomic no. 37) is
Which of these undergo polymerisation?