Science (English Medium) इयत्ता १२ - CBSE Question Bank Solutions for Chemistry

Give an example to show the effect of concentration of nitric acid on the formation of oxidation product.

On addition of small amount of \[\ce{KMnO4}\] to concentrated \[\ce{H2SO4}\], a green oily compound is obtained which is highly explosive in nature. Identify the compound from the following.

Which of the following reactions are disproportionation reactions?

(a) \[\ce{Cu^{+} -> Cu^{2+} + Cu}\]

(b) \[\ce{3MnO^{-}4 + 4H^{+} -> 2MnO^{-}4 + MnO2 + 2H2O}\]

(c) \[\ce{2KMnO4 -> K2MnO4 + MnO2 + O2}\]

(d) \[\ce{2MnO^{-}4 + 3Mn^{2+} + 2H2O -> 5MnO2 + 4H^{+}}\]

Which of the following is amphoteric oxide?

\[\ce{Mn2O7, CrO3, Cr2O3, CrO, V2O5, V2O4}\]

\[\ce{KMnO4}\] acts as an oxidising agent in alkaline medium. When alkaline \[\ce{KMnO4}\]  is treated with \[\ce{KI}\], iodide ion is oxidised to ______.

Generally transition elements and their salts are coloured due to the presence of unpaired electrons in metal ions. Which of the following compounds are coloured?

(i) \[\ce{KMnO4}\]

(ii) \[\ce{Ce(SO4)2}\]

(iii) \[\ce{TiCl}\]

(iv) \[\ce{Cu2 Cl2}\]

In the form of dichromate, \[\ce{Cr (VI)}\] is a strong oxidising agent in acidic medium but \[\ce{Mo (VI)}\] in \[\ce{MoO3}\] \[\ce{and W (VI)}\] in \[\ce{WO3}\] are not because:

(i) \[\ce{Cr(VI)}\] is more stable than \[\ce{Mo(VI)}\] and  \[\ce{and W(VI)}\].

(ii) \[\ce{Mo(VI)}\] and \[\ce{and W(VI)}\] are more stable than  \[\ce{Cr(VI)}\].

(iii) Higher oxidation states of heavier members of group-6 of transition series are more stable.

(iv) Lower oxidation states of heavier members of group-6 of transition series are more stable.

When \[\ce{Cu^2+}\] ion is treated with \[\ce{KI}\], a white precipitate is formed. Explain the reaction with the help of chemical equation.

When orange solution containing \[\ce{Cr2O^{2-}7}\] ion is treated with an alkali, a yellow solution is formed and when \[\ce{H^+}\] ions are added to yellow solution, an orange solution is obtained. Explain why does this happen?

How can propan-2-one be converted into tert- butyl alcohol?

Why is the reactivity of all the three classes of alcohols with conc. \[\ce{HCl}\] and \[\ce{ZnCl2}\] (Lucas reagent) different?

Explain a process in which a biocatalyst is used in industrial preparation of a compound known to you.

Amongst the following, the strongest base in aqueous medium is ______.

Benzylamine may be alkylated as shown in the following equation:

\[\ce{C6H5CH2NH2 + R - X -> C6H5CH2NHR}\]

Which of the following alkylhalides is best suited for this reaction through S_N1 mechanism?

Which of the following reagents would not be a good choice for reducing an aryl nitro compound to an amine?

In order to prepare a 1° amine from an alkyl halide with simultaneous addition of one \[\ce{CH2}\] group in the carbon chain, the reagent used as source of nitrogen is ______.

The source of nitrogen in Gabriel synthesis of amines is ______.

Amongst the given set of reactants, the most appropriate for preparing 2° amine is ______.

The best reagent for converting 2–phenylpropanamide into 2-phenylpropanamine is ______.

The best reagent for converting, 2-phenylpropanamide into 1- phenylethanamine is ______.