CBSE 11th Standard Chemistry Subject The p-block Elements Ncert Exemplar 3 Mark Questions With Solution 2021
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CBSE 11th Standard Chemistry Subject The p-block Elements Ncert Exemplar 3 Mark Questions With Solution 2021
11th Standard CBSE
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Reg.No. :
Chemistry
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Three pairs of compounds are given below, Identify that compound in each of the pairs which has group 13 element in more stable oxidation state. Give reason for your choice. State the nature of bonding also.
AlCl3, AlCl.(a) -
Three pairs of compounds are given below, Identify that compound in each of the pairs which has group 13 element in more stable oxidation state. Give reason for your choice. State the nature of bonding also.
InCl3, InCl(a) -
A tetravalent element forms monoxide and dioxide withoxygen. When air is passed over heated element(1273 K), Producer gas is obtained. Monoxide of the element is powerful reducing agent and reduces ferric oxide to iron. Identify the element and write formulas of its monoxide and dioxide.
Write chemical equations for the formation of prodecur gas and reduction of ferric oxide with the monoxide.(a) -
Identify the compounds A, X and Z in the following reactions,
\(A+2HCI+5{ H }_{ 2 }O\rightarrow 2NaCl+X\)
\(X \ \xrightarrow [ \Delta ]{ 370K } HBO_{ 2 }\xrightarrow [ \Delta ]{ >370K } Z\)(a) -
Identify the compounds A, X and Z in the following reactions,
\(Z+3LiAlH_{ 4 }\rightarrow X+3LiF+3AlF_{ 3 }\)
\( X+6{ H }_{ 2 }O\rightarrow Y+6{ H }_{ 2 }\)
\(X+3O_{ 2 }\underrightarrow { \Delta } B_{ 2 }O_{ 3 }+3{ H }_{ 2 }O\)(a)
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CBSE 11th Standard Chemistry Subject The p-block Elements Ncert Exemplar 3 Mark Questions With Solution 2021 Answer Keys
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Due to absence of d-orbitals, Al does not show inert pair effect. Therefore, its most stable oxidation state is +3. Thus, AlCl3 is much more stable AlCl. Further, in the solid or the vapour state, AlCl3 is covalent in nature but in aqueous solutions, it ionises to form Al3+(aq) and Cl-(aq)ions.
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Due to inert pair effect, indium exists in both +1 and +3 oxidation states, out of which +3 oxidation state is more than +1 oxidation state. In other words, InCl3 is more stable than InCl. Being unstable, InCl undergoes disproportionation reaction.
\(3InCl(aq)\rightarrow 2In(s)+In^{ 3+ }(aq)+3Cl^{ - }(aq)\) -
Producer gas is a mixture of CO and N2, therefore, the tetravalent element is carbon and its monoxide and dioxide are CO and CO2 respectively.
\(2C(s)+\underbrace { O_{ 2 }(s)+4N_{ 2 }(g) }_{ Air } \overset { 1273k }{ \rightarrow } \underbrace { 2CO(g)+4N_{ 2 }(g) }_{ Producer \ gas } \)
The carbon monoxide is a strong reducing agent and reduces ferric oxide to iron.
\(Fe_{ 2 }O_{ 3 }(s)+3CO(g)\overset { \Delta }{ \rightarrow } 2Fe(s)+3CO_{ 2 }(g)\) -
\(Na_{ 2 }B_{ 4 }{ O }_{ 7 }+2HCl+5{ H }_{ 2 }O \ \rightarrow \ 2NaCl+4H_{ 3 }BO_{ 3 }\)
Borax(A) Orthoboric acid(X)
\(H_{ 3 }BO_{ 3 } \ \underrightarrow { \Delta ,370K } \ HBO_{ 2 }+{ H }_{ 2 }O\)
(X) Metaboric acid
\(4 \ HBO_{ 2 }\xrightarrow [ \Delta ,>370K ]{ -H_{ 2 }O } [{ H }_{ 2 }B_{ 4 }{ O }_{ 7 }]\underrightarrow { Red \ heat } \ 2{ B }_{ 2 }{ O }_{ 3 }+H_{ 2 }O\)
Tetraboric acid Boron trioxide -
\(4BF_{ 3 }+3LiAlH_{ 4 }\rightarrow 2B_{ 2 }H_{ 6 }+3LiF+3AlF_{ 3 }\)
Boron trifluride(Z) Diborane(X)
\(B_{ 2 }H_{ 6 }+6H_{ 2 }O\rightarrow 2H_{ 3 }BO_{ 3 }+6H_{ 2 }\)
(X) Orthoboric acid(Y)
\(B_{ 2 }H_{ 6 }+3O_{ 2 }\underrightarrow { \Delta } B_{ 2 }O_{ 3 }+3{ H }_{ 2 }O\)
(X)
