List of top Chemistry Questions

For the reaction :
\(2AgCl(s) + H_2(g) (0.4 \text{ atm}) \rightarrow 2Ag(s) + 2H^+(0.1 \text{ M}) + 2Cl^-(0.2 \text{ M})\)
Calculate emf of the cell at \(25 \text{ } ^\circ\text{C}\).
Given : \(\Delta G^\circ = -43500 \text{ J mol}^{-1}\)
\([\log 10 = 1, 1 \text{ F} = 96500 \text{ C mol}^{-1}]\)
Calculate emf and \(\Delta G\) for the following cell at \(298 \text{ K}\) :
\(Mg(s) / Mg^{2+}(0.01 \text{ M}) // Ag^+(0.001 \text{ M}) / Ag(s)\)
Given : \(E^\circ_{Mg^{2+}/Mg} = -2.37 \text{ V}\), \(E^\circ_{Ag^+/Ag} = +0.80 \text{ V}\)
\([1 \text{ F} = 96500 \text{ C mol}^{-1}, \log 10 = 1]\)
Why is \(-NH_2\) group of aniline acetylated before carrying out nitration?
How can you convert aniline to benzonitrile?
A compound ‘X’ with molecular formula \(C_3H_9N\) reacts with Hinsberg reagent to give a product insoluble in alkali. Identify ‘X’.
Write structural formulae of the compound A and B:
\(CH_3CONH_2 \xrightarrow{NaOBr} A \xrightarrow[Base]{C_6H_5COCl} B\)
The reaction of amines with mineral acids to form ammonium salts shows that these are basic in nature. Aliphatic amines are stronger bases than ammonia whereas aromatic amines are weaker bases than ammonia. Aliphatic and aromatic primary and secondary amines react with acid chlorides, anhydrides and esters by nucleophilic substitution reaction. The main problem encountered during electrophilic substitution reactions of aromatic amines is that of their high reactivity. Substitution tends to occur at ortho-and para-positions. Hinsberg reagent is used for the identification and distinction between primary, secondary and tertiary amines. Aryldiazonium salts, usually obtained from arylamines, undergo replacement of the diazonium group with a variety of nucleophiles to provide advantageous methods for producing aryl halides, cyanides, phenols and arenes.

30(a)(i). Why \(CH_3 - NH_2\) is a stronger base than \((CH_3)_3N\) in aqueous solution?
\( [NiCl_4]^{2-} \) is paramagnetic while \( [Ni(CO)_4] \) is diamagnetic though both are tetrahedral. Why? [At. No. Ni=28]
Using CFT, write electronic configuration for: (i) \( [CoF_6]^{3-} \) (ii) \( [Co(NH_3)_6]^{3+} \). [At. No. Co=27]
The Valence Bond Theory (VBT) explains the formation, magnetic behaviour and geometry of coordination compounds. The Crystal Field Theory (CFT) of coordination compounds is based on the effect of different crystal fields (provided by the ligands taken as point charges), on the degeneracy of d-orbital energies of the central metal atom/ion. The splitting of the d-orbitals provides different electronic arrangements in strong and weak crystal fields. Answer the following questione

29(a). In octahedral crystal field, energies of which d-orbitals will be raised when ligands approach? Give reason.
Calculate the boiling point of a solution containing 0.61 g of benzoic acid (122 \( g mol^{-1} \)) in 5 g of \( CS_2 \) in which it dimerises to 88%. \( T_b^\circ(CS_2) = 46.2^\circ C, K_b = 2.3 K kg mol^{-1} \).
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.
How can you distinguish between Aldehydes and Ketones using the Tollen’s or Fehling’s test?
Explain the SN1 and SN2 mechanisms with suitable examples and reactivity orders.
Differentiate between DNA and RNA.
Why is Phenol more acidic than alcohols?
What is Lanthanoid Contraction and what are its consequences?
State Raoult’s Law for volatile solutes and explain its deviations.
Define Molar Conductivity and explain its variation with concentration for strong and weak electrolytes.
Explain the difference between Physisorption and Chemisorption.
Define Colligative Properties and provide two examples.
Calculate the EMF of a cell using the Nernst Equation.
Discuss Werner’s Theory of coordination compounds.
For the first order thermal decomposition reaction, following data was obtained : Calculate rate constant.
[Given : log 3 = 0.48]