List of top Chemistry Questions

Consider the following reaction:
\[ \text{S(s)} + \frac{3}{2} \text{O}_2 \text{(g)} \to \text{SO}_3 \text{(g)} + 2x \text{ K} \] \[ \text{SO}_2 \text{(g)} + \frac{1}{2} \text{O}_2 \text{(g)} \to \text{SO}_3 \text{(g)} + y \text{ K} \] Calculate $ \Delta H $ for the following reaction (K):
\[ \text{S(s)} + \text{O}_2 \text{(g)} \to \text{SO}_2 \text{(g)} \]

Choose the correct option for structures of A and B, respectively:

The correct order of stability of following carbocations is:

Identify product [A], [B], and [C] in the following reaction sequence.

Total number of electrons in chromium (Z = 24) for which the value of azimuthal quantum number (l) is 1 and 2.

HA $ (aq) \rightleftharpoons H^+ (aq) + A^- (aq) $ The freezing point depression of a 0.1 m aqueous solution of a monobasic weak acid HA is 0.20 °C. The dissociation constant for the acid is Given: $ K_f(H_2O) = 1.8 \, \text{K kg mol}^{-1} $, molality ≡ molarity

Match List - I with List - II:

List - I:
(A) Amylase
(B) Cellulose
(C) Glycogen
(D) Amylopectin

List - II:
(I) β-C1-C4 plant
(II) α-C1-C4 animal
(III) α-C1-C4 α-C1-C6 plant
(IV) α-C1-C4 plant

Which of the following pair of ions are same coloured?

Match List-I with List-II.

Given below are two statements:

Statement (II): Structure III is most stable, as the orbitals having the lone pairs are axial, where the $ \ell p - \beta p $ repulsion is minimum. In light of the above statements, choose the most appropriate answer from the options given below:

The hydration energies of $ K^+ $ and $ Cl^- $ are $ -x $ and $ -y $ kJ/mol respectively. If lattice energy of KCl is $ -z $ kJ/mol, then the heat of solution of KCl is :

The products formed in the following reaction sequence are:

In the following substitution reaction:

Which one of the following about an electron occupying the 1 s orbital in a hydrogen atom is incorrect ? (Bohr's radius is represented by $\mathrm{a}_{0}$ )

For the reaction A(g) $\rightleftharpoons$ 2B(g), the backward reaction rate constant is higher than the forward reaction rate constant by a factor of 2500, at 1000 K.
[Given: R = 0.0831 atm $mol^{–1} K^{–1}$]
$K_p$ for the reaction at 1000 K is:

Glucose on reaction with HCN forms a compound 'A'. Acid hydrolysis of A gives B. The molecular formula of B is:

At T(K), the following gaseous equilibrium is established. W + X $ \rightleftharpoons $ Y + Z The initial concentration of W is two times to the initial concentration of X. The system is heated to T(K) to establish the equilibrium. At equilibrium the concentration of Y is four times to the concentration of X. What is the value of $K_c$?

Choose the incorrect statement from the following

At what temperature (in K) the rms velocity of SO$_2$ molecules is equal to rms velocity of O$_2$ molecules at $27 \, ^\circ\text{C}$?

The structure of the product 'Z' in the reaction sequence is: \[ \text{CHO} \] \[ \mid \] \[

The number of amphoteric oxides from the following is
$\mathrm{CO_2, GeO_2, SnO_2, PbO_2, CO, GeO, SnO, PbO}$

At 298 K, the value of K$_p$ for N$_2$O$_4$(g) $\rightleftharpoons$ 2NO$_2$(g) is 0.113 atm. The partial pressure of N$_2$O$_4$ at equilibrium is 0.2 atm. What is the partial pressure (in atm) of NO$_2$ at equilibrium ?

For a first-order reaction, the rate constant $ k $ is $ 1.386 \times 10^{-3} \, \text{s}^{-1} $. What is the half-life $ t_{1/2} $ of the reaction? (Use $ \ln 2 = 0.693 $)

What are X and Y respectively in the following reaction sequence? ($anhy = \text{anhydrous}$) \[ \text{C}_6\text{H}_5\text{N}_2^+\text{X}^- \xrightarrow{\text{C}_2\text{H}_5\text{OH}} \text{X} \xrightarrow{\text{CO, HCl, anhy. AlCl}_3} \text{Y} \] % The question implies the first X is an anion, the second X is an organic product. Let's call the organic product P1 to avoid confusion. % So, C6H5N2+Anion- → P1 → Y

How many molecules are present in 4.4 grams of CO$_2$?
(Molar mass of CO$_2$ = 44 g/mol, Avogadro's number = $6.022 \times 10^{23}$)