List of top Chemistry Questions

Define the following terms with a suitable example in each case : \[ (i)\ \text{Ambidentate ligand} \] \[ (ii)\ \text{Double salt} \]

Write IUPAC names of the following compounds : \[ (i)\ [PtCl_2(en)_2]SO_4 \] \[ (ii)\ (NH_4)_2[CoF_4] \]

Assertion (A) : Order of reaction is not applicable for elementary reaction but applicable for complex reaction. Reason (R) : Order of reaction is an experimental quantity.

Explain why, on addition of 1 mol of KCl to 1 litre of water, the boiling point of water increases, while the addition of 1 mol of methyl alcohol to 1 litre of water decreases the boiling point.

Assertion (A) : Phenol is more acidic than 4-methylphenol. Reason (R) : The presence of an electron releasing group in phenol makes it more acidic.

Assertion (A) : Separation of Zr and Hf is difficult. Reason (R) : Zr and Hf have almost identical atomic and ionic radii due to lanthanoid contraction.

The boiling point of an azeotropic mixture of water and nitric acid is more than that of pure water and nitric acid. The mixture shows :

For the reaction \(2A \rightarrow 3B\), the rate of reaction \(\frac{d[B]}{dt}\) is equal to :

In aqueous acidified solution, CrO$_4^{2-}$ ion converts to which of the following ?

On hydrolysis, which of the following carbohydrates gives only glucose ?

Which reagent is used to distinguish between C$_2$H$_5$NH$_2$ and (C$_2$H$_5$)$_2$NH ?

The oxidation number of Co in [Co(NH$_3$)$_5$(ONO)]SO$_4$ is :

According to Werner’s theory, the primary valencies of the central metal atom :

Among the following, which one has the lowest value of pK$_b$ ?

The dehydration of 1$^\circ$, 2$^\circ$ and 3$^\circ$ alcohols follows the order :

The mole fraction of a solute in 2.0 molal aqueous solution is :

On electrolysis of very dilute aqueous solution of NaCl using platinum electrodes :

Which of the following compounds is most reactive towards nucleophilic substitution reaction with aqueous NaOH ?

Answer the following: \[ (a)(i)\;\text{Calculate the electrode potential of a half-cell for zinc electrode dipping in }0.01M\;ZnSO_4\text{ solution at }25^\circ C. \] \[ E^\circ_{Zn^{2+}/Zn}=-0.76V,\quad \log 10=1 \] \[ (a)(ii)\;\text{Write anode, cathode and overall reaction involved in dry cell.} \] \[ (a)(iii)\;\text{Equilibrium constant }(K_c)\text{ is related to }E^\circ_{\text{cell}},\text{ but not to }E_{\text{cell}}.\text{ Why?} \]

Answer the following: \[ (a)(i)\;\text{Describe giving reason which one of the following pairs has the property indicated:} \] \[ (I)\;Fe\text{ or }Cu-\text{higher melting point} \] \[ (II)\;Ti^{3+}\text{ or }Sc^{3+}-\text{coloured in aqueous solution} \] \[ (III)\;Cr\text{ or }Zn-\text{higher third ionisation enthalpy} \] \[ (a)(ii)\;\text{Write the ionic equations for the oxidizing action of }MnO_4^-\text{ in acidic medium with:} \] \[ (I)\;Fe^{2+}\text{ ion} \] \[ (II)\;I^-\text{ ion} \]

Answer the following: \[ (a)(i)\;\text{Write the product(s) when:} \] \[ (I)\;\text{One mol of ethanal is treated with }1\text{ mol of }CH_3OH\text{ in the presence of dry }HCl\text{ gas.} \] \[ (II)\;\text{Benzaldehyde is treated with conc. }NaOH. \] \[ (III)\;\text{Ethanoic acid is heated in the presence of }P_2O_5. \] \[ (a)(ii)\;\text{Write a simple chemical test to distinguish between ethanal and propanal.} \] \[ (a)(iii)\;\text{Write the name of the reagent to transform allyl alcohol to propenal.} \]

How will you obtain the following from benzenediazonium chloride? Give chemical equations involved: \[ (a)\;\text{Chlorobenzene} \] \[ (b)\;\text{Benzene} \] \[ (c)\;\text{Benzonitrile} \]

Answer the following case-based questions on biomolecules: \[ (a)\;\text{Write the name of basic building units of proteins and nucleic acids. How can you differentiate between fibrous and globular proteins on the basis of their structures?} \] \[ (b)(i)\;\text{What products would be formed when a nucleotide from DNA containing thymine is hydrolyzed?} \] OR \[ (b)(ii)\;\text{Write one structural difference between DNA and RNA.} \] \[ (c)\;\text{Give one example each of a fat-soluble vitamin and a water-soluble vitamin.} \]

An organic compound \(A\) with molecular formula \(C_3H_5N\) on reaction with \(C_6H_5MgBr\) followed by hydrolysis gives compound \(B\). Compound \(B\) forms orange-red precipitate with 2,4-DNP reagent and does not give iodoform test. It neither reduces Tollens' or Fehling's reagent nor decolourises bromine water. On drastic oxidation with chromic acid it gives carboxylic acid \(C\) having molecular formula \(C_7H_6O_2\). Identify \(A\), \(B\), and \(C\). Write the reactions.