List of top Chemistry Questions asked in CBSE CLASS XII

Give the structures of A, B, and C in the following reactions:

Write the major product(s) in the following reactions: 

Give simple chemical tests to distinguish between the following pairs of compounds: (1) \( \text{C}_6\text{H}_5\text{COCH}_3 \text{ and } \text{C}_6\text{H}_5\text{COCH}_2\text{CH}_3 \)

Write the hybridization and magnetic character of the complex \([Ni(CO)_4]\) on the basis of valence bond theory.
[Atomic No. Ni = 28]

Out of \([CoF_6]^{3-}\) and \([Co(C_2O_4)_3]^{3-}\), which complex is:} 
(i) More stable? 
(ii) The high-spin complex? 
 

Write the electronic configuration of \(d^5\) in terms of \( t_{2g} \) and \( e_g \) in an octahedral field as: 
\( \Delta_o>P \)
 

Calculate the \( \Delta G^\circ \) and \( \log K_c \) for the following cell reaction:
\(\text{Fe (s)} + \text{Ag}^+ (aq) \rightleftharpoons \text{Fe}^{2+} (aq) + \text{Ag (s)}\)
Given: \( E^\circ_{\text{Fe}^{2+}/\text{Fe}} = -0.44 \, \text{V}, E^\circ_{\text{Ag}^+/ \text{Ag}} = +0.80 \, \text{V} \)
\( 1 F = 96500 \, \text{C mol}^{-1} \)

State Faraday's second law of electrolysis. How will the pH of aqueous NaCl solution be affected when it is electrolyzed?

Write any two advantages of fuel cells over primary and secondary batteries?

How many Faradays are required for the oxidation of one mole of \( \text{H}_2\text{O} \) to \( \text{O}_2 \)?

Calculate emf of the following cell at 25°C:
\(\text{Zn (s)} | \text{Zn}^{2+} (0.001M) || \text{Cd}^{2+} (0.1M) | \text{Cd (s)}\) Given: \( E^\circ_{\text{Zn}^{2+}/\text{Zn}} = -0.76 \, \text{V}, E^\circ_{\text{Cd}^{2+}/\text{Cd}} = -0.40 \, \text{V} \)
\([ \log 10 = 1 ]\)

Write the reaction involved in Hell-Volhard-Zelinsky reaction.

Why is geometrical isomerism not possible in tetrahedral complexes having two different types of unidentate ligands coordinated with the central metal?

Arrange the following complex ions in increasing order of their crystal field splitting energy (\( \Delta_0 \)):
\(\text{[Co(NH}_3\text{)}_6]^{3+}, \, \text{[CoF}_6]^{3-}, \, \text{[Co(CN)}_6]^{3-}\)

What is the difference between an ambidentate ligand and a bidentate ligand?

Arrange the following in decreasing order of their acidic strength:
\( \text{CH}_3\text{COOH}, \, \text{O}_2\text{N}-\text{CH}_2\text{COOH}, \, \text{HCOOH} \)

What is the structural feature that characterizes a reducing sugar?

What is the structural difference between nucleoside and nucleotide?

Name the reagent in the following reaction:
\( \text{CH}_3\text{CH} = \text{CH}-\text{CN} \xrightarrow{} \text{CH}_3\text{CH} = \text{CH}-\text{CHO} \)

Why do transition metals and their compounds act as good catalysts?

What is the cause of contraction in the atomic size of lanthanoids?

Define lanthanoid contraction. How does it affect the atomic radii of the third transition series and the second transition series?

In aqueous media, which is a stronger reducing agent — Cr³⁺ or Fe³⁺ and why?