List of top Chemistry Questions

A first order reaction is $50\%$completed in $1.26\times10^{14}S.$ How much time would it take for $100\%$ completion?

Reaction between \(N_2\) and \(O_2^–\) takes place as follows: 
\(2N_2 (g) + O_2 (g) ⇋ 2N_2O (g)\)
If a mixture of \(0.482 \ mol\) \(N_2\) and \(0.933\  mol\) of \(O_2\) is placed in a \(10\  L\) reaction vessel and allowed to form \(N_2O\) at a temperature for which \(K_c = 2.0 × 10^{–37}\), determine the composition of equilibrium mixture.

The chemical inertness of $N_2$ is attributed to

The ratio of the velocities of ${CH}_4$ and $O_2$ molecules, so that they are associated with de-Broglie waves of equal wavelength is:

Compare the stability of +2 oxidation state for the elements of the first transition series

The moiety present at the 5' end of ribose sugar in a polynucleotide is

Explain why the following systems are not aromatic?

Match the following prefixes with their multiples:

S.No	Prefixes	Multiples
(i)	micro	106
(ii)	deca	109
(iii)	mega	10–6
(iv)	giga	10–15
(v)	femto	10

The ionization constant of benzoic acid is 6.46 × 10^–5 and K_sp for silver benzoate is 2.5 × 10^–13. How many times is silver benzoate more soluble in a buffer of pH 3.19 compared to its solubility in pure water?

What sorts of information can you draw from the following reaction?
(CN)₂( g)+2OH⁻(aq)\(\rightarrow\)CN⁻(2aq)+CNO⁻(aq)+H₂O(l)

The solubility product constant of Ag₂CrO₄ and AgBr are 1.1×10^–12 and 5.0×10^–13 respectively. Calculate the ratio of the molarities of their saturated solutions.

Balance the following redox reactions by ion-electron method: 
(a)MnO₄^- _(aq) + I ^- _(aq) → MnO_2(s) + I₂(s) (in basic medium)
(b) MnO₄^- _(aq) + SO_2(g) → Mn₂⁺_(aq) +HSO₄^- _(aq) (in acidic solution)
(c) H₂O_2(aq)+Fe₂⁺_(aq) → Fe₃⁺ _(aq) + H₂O (l) (in acidic solution)
(d) Cr₂O₇^2-+ SO_2(g) → Cr³⁺ _(aq) +SO₄^2- _(aq) (in acidic solution)

Which of the following carbocation is most stable?

Determine the molecular formula of an oxide of iron, in which the mass per cent of iron and oxygen are 69.9 and 30.1, respectively.

Explain the principle of paper chromatography.

Differentiate between the principle of estimation of nitrogen in an organic compound by (i) Dumas method and (ii) Kjeldahl’s method.

Discuss the chemistry of Lassaigne’s test.

Why is Wurtz reaction not preferred for the preparation of alkanes containing odd number of carbon atoms? Illustrate your answer by taking one example

Calculate the entropy change in surroundings when \(1.00\ mol\) of \(H_2O(l)\) is formed under standard conditions. \(∆_fH^Θ= –286\ kJ mol^{-1}\).

Comment on the thermodynamic stability of \(NO(g)\), given
\(\frac 12N_2(g) +\frac 12O_2(g)→NO(g); \ \ \ \ ∆_rH^Θ= 90\ kJ mol^{-1}\)
\(NO(g) +\frac 12 O_2(g)→NO_2(g);\ \ \  ∆_rH^Θ= –74\ kJ mol^{-1}\)

The equilibrium constant for a reaction is \(10\). What will be the value of \(∆G^Θ\)?
\(R= 8.314\ JK^{-1} mol^{-1}, T=300\ K\)

For the reaction
\(2A(g)+B(g)→2D(g)\)
\(∆U^Θ= -10.5\ kJ\) and \(∆S^Θ= -44.1\ JK^{-1}\).
Calculate \(∆G^Θ\) for the reaction, and predict whether the reaction may occur spontaneously.

For the reaction, \(2Cl(g)→Cl_2(g)\), what are the signs of \(∆H\) and \(∆S\) ?