List of top Chemistry Questions asked in CBSE CLASS XII

Define Pseudo first order reaction with an example.
Give reasons for the following: (a) Reduction with iron scrap and HCl is preferred for the preparation of amines from nitro compounds.
(b) Lower aliphatic amines are soluble in water.
(c) Pyridine is used in the acylation reaction of amines.
(d) Although amino group is o- and p-directing in aromatic electrophilic substitution reactions, aniline on nitration gives a substantial amount of m-nitroaniline.
Write the chemical equation for the following: (a) Hydration of propene in presence of an acid
(b) Reaction between Ethyl bromide and C2H5ONa
(c) Reaction between Dimethyl ether and Hydrogen iodide
Why are iron pipes usually coated with zinc?
Why does mercury cell give a constant voltage throughout its life?
Using valence bond theory, predict: (a) Hybridisation of central metal atom of the complex \([Co(NH_3)_6]^{3+}\)
(b) Its shape and magnetic behaviour
(c) Whether it is a high spin or a low spin complex
[Atomic number: $CO$ = 27]

Why is \( pK_a \) of ClCH2COOH lower than the \( pK_a \) of CH3COOH?

Why do amino acids show amphoteric behaviour?
What happens when D-Glucose is treated with hydroxylamine?
Why is sulphuric acid not used during the reactions of alcohols with KI?
Write the structure of 1-chloro-4-ethylcyclohexane.
What is an ambident nucleophile? Give one example.
Write IUPAC name of the given complex: \( K_3[Cr(C_2O_4)_3] \)

Why is \([Ti(H_2O)_6]^{3+}\) coloured?

Assertion (A): Zn, Cd and Hg are not regarded as transition elements.
Reason (R): Zn, Cd and Hg do not have partially filled d-orbitals in their ground state or in any one of their common oxidation states.
Oxidation state of central metal atom in the given complex is: \[ [Co(NH_3)_4(H_2O)_2]Cl_3 \]
What would be the major product of the given reaction? \[ HCHO + CH_3MgI \xrightarrow{H_2O} \; ? \]
Pentan-2-one and Pentan-3-one can be distinguished by:
Solutions of two electrolytes X and Y are diluted. Molar conductivity of X increases 25 times whereas that of Y increases 1.5 times. Which one is a stronger electrolyte?
Which of the following reactions is a halogenated exchange reaction:
The most common oxidation state for all lanthanoids is:
The diamagnetic species is :
At. No. Co = 27, Fe =26, Ni= 28]
The complex ions \([Co(NH_3)_5(NO_2)]^{2+\) and \([Co(NH_3)_5(ONO)]^{2+}\) are called}

Which one of the following has the highest dipole moment?

(i)CH2Cl2

(ii)CHCl3

(iii)CCl4

Azeotropic mixture of water and HCl boils at 381.5 K. By distilling the mixture it is possible to obtain