List of top Chemistry Questions

In the Hinsberg method for separation of primary, secondary, and tertiary amines, the reagent used is:
Which of the following is the softest metal?
Which one of the following amines gives an alcohol on reaction with HNO₂?
Which of the following complex ions is not optically active?
A solution of acetone in ethanol:
According to Werner’s theory of coordination compounds:
Which of the following compounds would be hydrolyzed by aqueous KOH most easily?
Williamson synthesis of preparing unsymmetrical ether is:
Which of the following is not a colligative property?
Which of the following compounds will give a positive Iodoform test?
According to the generally accepted definition of the ideal solution there are equal interaction forces acting between molecules belonging to the same or different species. (This is equivalent to the statement that the activity of the components equals the concentration.) Strictly speaking, this concept is valid in ecological systems (isotopic mixtures of an element, hydrocarbons mixtures, etc.). It is still usual to talk about ideal solutions as limiting cases in reality since very dilute solutions behave ideally with respect to the solvent. This law is further supported by the fact that Raoult’s law empirically found for describing the behaviour of the solvent in dilute solutions can be deduced thermodynamically via the assumption of ideal behaviour of the solvent.
Ribose and 2-deoxyribose have an important role in biology. Among the most important derivatives are those with phosphate groups attached at the 5 position. Mono-, di- and tri-phosphate forms are important, as well as 3-5 cyclic monophosphates. Purines and pyrimidines form an important class of compounds with ribose and deoxyribose. When these purine and pyrimidine derivatives are coupled to a ribose sugar, they are called nucleosides.

The reaction between A2 (g) and B2 (g) was carried out in a sealed isothermal container. The rate law for the reaction was found to be:

Rate = \( k[\text{A}_2][\text{B}_2] \)

If 1 mole of A2 (g) was added to the reaction chamber and the temperature was kept constant, then predict the change in rate of the reaction and the rate constant.

For the reaction:
2H$_2$O$_2$ $\xrightarrow{I^-}$ 2H$_2$O + O$_2$
Given mechanism:
(I) H$_2$O$_2$ + I$^-$ → H$_2$O + IO$^-$ (slow)
(II) H$_2$O$_2$ + IO$^-$ → H$_2$O + I$^-$ + O$_2$ (fast)
(1) Write rate law for the reaction.
(2) Write the overall order and molecularity of the reaction.
Arrange the following compounds as asked:
(a) In decreasing order of pKb values
C2H5NH2, (C2H5)2NH, C6H5NHCH3, C6H5NH2
(b) In increasing order of boiling point
C2H5OH, C2H5NH2, (CH3)2NH
(c) In increasing order of solubility in water
C6H5NH2, (C2H5)2NH, C2H5NH2

Give explanation for each of the following observations:

(a) With the same d-orbital configuration (d4), Mn3+ ion is an oxidizing agent whereas Cr2+ ion is a reducing agent.

(b) Actinoid contraction is greater from element to element than that among lanthanoids.

(c) Transition metals form a large number of interstitial compounds with H, B, C, and N.

Calculate the cell voltage of the voltaic cell which is set up by joining the following half-cells at 25°C:
Al/Al3+ (0.002 M) and Ni/Ni2+ (0.002 M)
Given: \( E^\circ_{\text{Ni}^{2+}/\text{Ni}} = -0.25 \, \text{V} \)
\( E^\circ_{\text{Al}^{3+}/\text{Al}} = -1.66 \, \text{V} \)
\( \log 5 = 0.6990 \)

An aromatic compound ‘A’ with molecular formula C8H8O gives positive 2,4-DNP test. It gives yellow precipitate of compound ‘B’ on treatment with sodium hypoiodite. Compound ‘A’ does not react with Tollen’s or Fehling’s reagent; on drastic oxidation with KMnO4 it forms a carboxylic acid ‘C’. Elucidate the structures of A, B, and C. Also give their IUPAC names.

Identify and draw the main products formed in the following chemical reactions:

Name the type of isomerism exhibited and draw isomers:

(I) [Co(NH3)6][Cr(CN)6]

(II) [Co(en)3]3+

(III) [Co(NH3)3(NO2)3]

A compound ‘A’ with molecular formula C4H8O gives positive 2,4-DNP test. It gives yellow precipitate of compound ‘B’ on treatment with sodium hydrogen sulphite. Compound ‘A’ does not react with Tollen’s or Fehling’s reagent; on oxidation with KMnO4, it forms carboxylic acid ‘C’. Elucidate the structures of ‘A’, ‘B’ and ‘C’. Also give their IUPAC names.

Out of Ti3+, Cr3+, Fe2+ and Ni2+ ions, the one which is the most stable ion in aqueous solution is:

Which of the following properties of transition metals enables them to behave as catalysts?
Name and define the cell which was used for providing electric power in the Apollo space programme. Also write its one advantage.
Complete the following reactions by writing the structural formulae of ‘A’ and ‘B’:

(i) \( \text{CH}_3\text{CH} = \text{CH}_2 \)
\( \xrightarrow{\text{HBr, Peroxide}} \) ‘A’ \( \xrightarrow{\text{aq. KOH}} \) ‘B’

(ii) \( \text{CH}_3\text{CH}_2\text{CH(Cl)CH}_3 \)
\( \xrightarrow{\text{alc. KOH}, \Delta} \) ‘A’ \( \xrightarrow{\text{HBr}} \) ‘B’

(iii) ‘A’ \( \xrightarrow{\text{Mg}} \) \( \text{CH}_3\text{CH}_2\text{CH}_2\text{MgCl} \) \( \xrightarrow{\text{H}_2\text{O, H}^+} \) ‘B’ (Main product)