List of top Chemistry Questions asked in CBSE CLASS XII

What type of battery is Mercury cell? Why it is more advantageous than dry cell? Write overall reaction taking place in Mercury cell.
Answer the following :
(i) Why is the Equilibrium Constant (\(K_c\)) related to \(E^{\circ}_{cell}\) and not to \(E_{cell}\)?
(ii) Two metals ‘A’ and ‘B’ have standard electrode potential values of \(-0.24\) V and \(+0.80\) V respectively. Which of these will liberate hydrogen gas from dil. \(H_2SO_4\)?
(iii) Write the cell reaction which occurs in lead storage battery when it is in charging.
For the first order thermal decomposition reaction, following data was obtained : Calculate rate constant.
[Given : log 3 = 0.48]
Glycosidic linkage.
Invert sugar.

Define the term:  Anomers. 
 

Nucleophilic addition of ammonia and its derivatives does not occur with carbonyl group in strongly acidic medium.
Alpha (\(\alpha\)) hydrogens of aldehydes and ketones are acidic in nature.

Give reason of the following
Carboxylic acids have higher boiling point than alcohols of comparable molecular masses. 
 

Write the reaction involved in Friedel-Crafts acylation of anisole.
Write the reaction involved in Kolbe’s reaction.
Write the reaction involved in Reimer-Tiemann reaction.
Out of ‘X’ and ‘Y’ , which one will form product with inversion of configuration and why?
Out of ‘X’ and ‘Y’, which one will undergo racemisation and why?
Differentiate between the following :
(i) Acidic amino acids and basic amino acids
(ii) Nucleotide and Nucleoside
Why are haloarenes less reactive towards nucleophilic substitution reaction? Give two reasons.
(i) Give a chemical test to show that \( [Co(NH_3)_5SO_4]Cl \) and \( [Co(NH_3)_5Cl]SO_4 \) are ionisation isomers.
(ii) What is meant by the 'Chelate effect'? Give an example.
What type of deviation from Raoult’s law is shown by mixture of ethanol and acetone? Give reason. What will happen to the boiling point of the solution on mixing ethanol and acetone?
Assertion (A) : The two strands of DNA are complementary to each other.
Reason (R) : The hydrogen bonds are formed between specific pairs of bases.
Assertion (A) : Components of azeotropes are easily separated by fractional distillation.
Reason (R) : Components of an azeotrope have same composition in liquid and vapour phase.
Assertion (A) : The presence of \( -OH \) group in phenols directs the incoming group to ortho and para positions.
Reason (R) : \( -OH \) group in phenols activates the aromatic ring towards electrophilic substitution reaction.
Benzene diazonium chloride on reaction with phenol in weakly basic medium gives
An example of non-reducing sugar is
Which of the following is 'not' true about enantiomers?
Aniline on direct nitration yields