List of top Chemistry Questions asked in CBSE CLASS XII

Write the main product in the following reaction:
ester to a primary alcohol
The resistance of 0.05 M CH\(_3\)COOH solution is found to be 100 ohm. If the cell constant is 0.0354 cm\(^{-1}\), calculate the molar conductivity of the acetic acid solution.
State Faraday's first law of electrolysis. How much charge in Faraday is required for the reduction of 1 mol of MnO\(_4^-\) to Mn\(^{2+}\)?
Give a simple chemical test to distinguish between ethanoic acid and ethanal.
Arrange the following in increasing order of their reactivity towards HCN: \[ \text{CH}_3\text{COCH}_3, \, (\text{CH}_3)_3\text{C} - \text{COCH}_3, \, \text{CH}_3\text{CHO} \]
Draw structure of the 2,4-dinitrophenylhydrazone of benzaldehyde.
How can you convert phenyl magnesium bromide to benzoic acid?
Write the IUPAC name of the following complex: [PtCl\(_2\)(en)\(_2\)](NO\(_3\))\(_2\)
Write the geometry and magnetic behaviour of the complex [Ni(CO)\(_4\)] on the basis of Valency Bond Theory (VBT).
What type of isomerism is shown by the complex [Co(NH\(_3\))\(_6\)][Cr(CN)\(_6\)]?
Out of [Co(NH\(_3\))\(_6\)]\(^{3+}\) and [Co(NH\(_3\))\(_4\)Cl\(_2\)]\(^+\), which complex is heteroleptic and why?
Draw the structures of optical isomers of [PtCl\(_2\)(en)\(_2\)]\(^{2+}\).
Account for the following:
1. Oxidation of aldehydes is easier as compared to ketones.
2. The alpha (α) hydrogen atoms of aldehydes are acidic in nature.
Write the products in the following reactions:
reaction of acetophenone
For the coordination compound on the basis of crystal field theory, write the electronic configuration for d\(^4\) ion if \(\Delta_o\) < P. Is the coordination compound a high spin or low spin complex?
How is the crystal field splitting energy for octahedral complex (\(\Delta_o\)) related to that of tetrahedral complex (\(\Delta_t\))?
The vapour pressure of a solvent at 283 K is 100 mm Hg. Calculate the vapour pressure of a dilute solution containing 1 mole of a strong electrolyte AB in 50 moles of the solvent at 283 K (assuming complete dissociation of solute AB).
Give the equations of reactions for the preparation of: (any three) (a) Phenol from chlorobenzene
(b) Salicyaldehyde from phenol
(c) 2-Methoxyacetophenone from anisole
Calculate emf of the following cell: \[ \text{Zn (s)} | \text{Zn}^{2+} (0.1 M) || \text{Sn}^{2+} (0.001 M) | \text{Sn (s)} \] Given: \[ E^\circ_{\text{Zn}^{2+}/\text{Zn}} = -0.76 \, \text{V}, \quad E^\circ_{\text{Sn}^{2+}/\text{Sn}} = -0.14 \, \text{V} \] \[ [\log 10 = 1] \]
Give reasons for the following: (a) Chlorine is ortho/para directing in electrophilic aromatic substitution reactions, though chlorine is an electron withdrawing group.
(b) Racemic mixture is optically inactive.
(c) Allyl chloride is hydrolysed more readily than n-propyl chloride.
The rate of a gaseous reaction triples when temperature is increased from 17°C to 27°C. Calculate the energy of activation for this reaction. $[Given : 2 303 R = 19 15 JK^{-1} mol^{-1}, log 3 = 0 48]$
In the following pair of compounds, which compound undergoes an $\text{S}_{N}$2 reaction faster and why?
compound undergoes an SN2
Why do transition metals have high enthalpy of atomization? Which element of the 3d-series has the lowest enthalpy of atomization?
Write the structures of A, B, and C in the following reactions:
structures of A, B, and C
Write the reaction involved in the following: Wolff-Kishner reduction
(b) Decarboxylation reaction
(c) Cannizzaro reaction