List of top Chemistry Questions

Identify the polysaccharide among the following :
Consider the following compounds : \[ C_2H_5NH_2,\quad (C_2H_5)_2NH,\quad C_6H_5CH_2NH_2,\quad NH_3,\quad C_6H_5NH_2 \] The correct increasing order of the above compounds on the basis of their basic strength is :
Assertion (A) : D (+) – Glucose is dextrorotatory in nature. Reason (R) : (+) represents dextrorotatory nature and D represents the configuration.
Actinoids show larger number of oxidation states :
The correct formula of Hinsberg’s reagent is :
The major product of carbylamine reaction is :
Consider the following reaction and identify A and B : \[ CH_3Cl + NaI \xrightarrow[\text{dry acetone}]{} A + B \]
Half-life (\(t_{1/2}\)) of a first order reaction is 1386 s. The value of rate constant is :
Which of the reactions is used in the conversion of a ketone into hydrocarbon ?
Which of the following reagents are used to prepare primary amines by Hoffmann bromamide degradation reaction ? \[ (i)\quad \begin{array}{c} O\\ || \end{array} R-C-NH_2 \] \[ (ii)\quad NaOH \] \[ (iii)\quad Br_2 \] \[ (iv)\quad CHCl_3 \]
(b)(i) Draw the structure of the semicarbazone of acetone.
(b)(iv) Write the reaction involved in Etard reaction.
(b)(ii) Why are \(\alpha\)-hydrogen atoms of aldehydes and ketones acidic in nature ?
(b)(iii) Arrange the following compounds in increasing order of their reactivity towards HCN : \[ (CH_3)_3C-CO-CH_3,\qquad CH_3COCH_3,\qquad CH_3CHO \]
(b)(v) Write the product when benzaldehyde reacts with \(Zn(Hg)/\)conc. HCl.
(a)(ii) Write a simple chemical test to distinguish between Ethanal and Propanal.
(a)(iii) Write the name of the reagent used to transform Allyl alcohol to Propenal.
(a)(i) Write the product(s) when : (I) One mol of ethanal is treated with 1 mol of \(CH_3OH\) in the presence of dry HCl gas. (II) Benzaldehyde is treated with conc. NaOH. (III) Ethanoic acid is heated in the presence of \(P_2O_5\).
(a)(i) Describe giving reason which one of the following pairs has the property indicated : (I) Fe or Cu -- higher melting point (II) (Ti^3+) or (Sc^3+) -- coloured in aqueous solution (III) Cr or Zn -- higher third ionisation enthalpy
(b)(ii) What happens when an acidic solution of the green compound (B) is allowed to stand for some time ? Also write the equation involved. What is this type of reaction called ?
(b)(i) A black-brown coloured solid (A) when fused with KOH in the presence of air, produces a dark green coloured compound (B) which on electrolytic oxidation in alkaline medium gives a dark purple coloured compound (C). Identify (A), (B) and (C). Write the reactions involved.
(a)(ii) Write the ionic equations for the oxidizing action of (MnO_4^-) in acidic medium with : (I) (Fe^2+) ion (II) (I^-) ion
(b)(ii)(I) Why does a mercury cell deliver a constant voltage for its entire life ?
(b)(i) The conductivity of \(0.001\,M\) solution of acetic acid is \(3.905\times10^{-5}\,S\,cm^{-1}\). Calculate its molar conductivity and degree of dissociation (\(\alpha\)). Given : \[ \lambda^\circ_{H^+}=349.6\,S\,cm^2\,mol^{-1} \] \[ \lambda^\circ_{CH_3COO^-}=40.9\,S\,cm^2\,mol^{-1} \]
(b)(ii)(II) Why is it necessary to use salt bridge in a galvanic cell ?