Ncert Solutions Chemistry Class 11th
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11.36. Thermodynamically the most stable form of carbon is
(a)diamond (b) graphite (c) fullerenes (d) coal
11.36. Thermodynamically the most stable form of carbon is
(a)diamond (b) graphite (c) fullerenes (d) coal
Thermodynamically the most stable form of carbon is graphite, i.e., option (b) is correct.
Upvote 
11.35. The type of hybridisation of boron in diborane is
(a) sp (b) sp2(c) sp3(d) dsp2
11.35. The type of hybridisation of boron in diborane is
(a) sp (b) sp2(c) sp3(d) dsp2
In B2H6, B is sp3-hybridized. Therefore, option (c) is correct.
Upvote 11.34. Boric acid is polymeric due to
(a) its acidic nature (b) the presence of hydrogen bonds
(c) its monobasic nature (d) its geometry
11.34. Boric acid is polymeric due to
(a) its acidic nature (b) the presence of hydrogen bonds
(c) its monobasic nature (d) its geometry
Boric acid is polymeric due to the presence of H-bonds. Therefore, option (b) is correct.
Upvote 11.33. An aqueous solution of borax is
(a) neutral (b) amphoteric (c) basic (d) acidic
11.33. An aqueous solution of borax is
(a) neutral (b) amphoteric (c) basic (d) acidic
Borax is a salt of a strong base (NaOH) and a weak acid (H3BO3), therefore, it is basic in nature, i.e., option (c) is correct.
Upvote 11.32. Give one method for industrial preparation and one for laboratory preparation of CO and CO2 each.
11.32. Give one method for industrial preparation and one for laboratory preparation of CO and CO2 each.
Laboratory preparation of carbon monoxide:
Formic acid is dehydrated with concentrated sulphuric acid at 373 K.
HCOOH → H2O + CO↑
Commercial preparation of CO:
Steam is passed over hot coke.
C + H2O → CO + H2
Laboratory preparation of carbon dioxide:
Calcium carbonate reacts with dilute HCl to fo
Upvote 11.31. Write balanced equations for:
Write balanced equations for:
(i) BF3 + LiH →
(ii) B2H6 + H2O →
(iii) NaH + B2H6 →
(iv) H3BO3(heat) →
(v) Al + NaOH →
(vi) B2H6 + NH3 →
11.31. Write balanced equations for:
Write balanced equations for:
(i) BF3 + LiH →
(ii) B2H6 + H2O →
(iii) NaH + B2H6 →
(iv) H3BO3(heat) →
(v) Al + NaOH →
(vi) B2H6 + NH3 →
The balanced equations are given below:
(i) 2BF3 + 6LiH → B2H6 + 6LiF
(ii) B2H6 + 6H2O → 2H3BO3 (orthoboric acid)
(iii) 2NaH + B2H6 →2Na [BH4] (sodium borohydride)
(iv) H3BO3 →HBO2 (metaboric acid) + H2O
4HBO2 →H2B4O7→ 2B2O3 (boron trio
Upvote 11.30. A certain salt X, gives the following results.
(i) Its aqueous solution is alkaline to litmus.
(ii) It swells up to a glassy material Y on strong heating.
(iii) When conc.H2SO4is added to a hot solution of X, white crystal of an acid Z separates out.
Write equations for all the above reactions and identify X, Y and Z. (Advance)
11.30. A certain salt X, gives the following results.
(i) Its aqueous solution is alkaline to litmus.
(ii) It swells up to a glassy material Y on strong heating.
(iii) When conc.H2SO4is added to a hot solution of X, white crystal of an acid Z separates out.
Write equations for all the above reactions and identify X, Y and Z. (Advance)
The compounds X, Y and Z are borax, sodium metaborate + boric anhydride and boric acid respectively.
When borax is heated, it first swells and then forms a transparent glass like bead of sodium meta borate and boric anhydride.
Na2B4O7 à2NaBO2+B2O3+10H2O
(Borax) (sodi
Upvote 11.29. What do you understand by (a) inert pair effect (b) allotropy and (c) catenation?
11.29. What do you understand by (a) inert pair effect (b) allotropy and (c) catenation?
(a) Inert pair effect: When the pair of electrons in the valence shell does not take part in bond formation, then this effect is called as inert pair effect.
(b)Allotropy: It is the property of the element by which an element can exist in two or more forms which have same chemical propert
Upvote 11.28. When metal X is treated with sodium hydroxide, a white precipitate (A) is obtained, which is soluble in excess of NaOH to give soluble complex (B). Compound (A) is soluble in dilute HCl to form compound (C). The compound (A) when heated strongly gives (D), which is used to extract metal. Identify (X), (A), (B), (C) and (D). Write suitable equations to support their identities.
11.28. When metal X is treated with sodium hydroxide, a white precipitate (A) is obtained, which is soluble in excess of NaOH to give soluble complex (B). Compound (A) is soluble in dilute HCl to form compound (C). The compound (A) when heated strongly gives (D), which is used to extract metal. Identify (X), (A), (B), (C) and (D). Write suitable equations to support their identities.
The compounds X, A, B, C and D are aluminium, aluminium hydroxide, sodium tetrahydrozoaluminate (III), aluminium chloride and alumina.
Aluminium reacts with NaOH to form white PPT of Al (OH)3→.
2Al + 3NaOH → Al (OH)3→ + 3Na+
Al (OH)3→ reacts with NaOH to form Na+ [Al (OH)4
Upvote 11.27. In some of the reactions thallium resembles aluminium, whereas in others it resembles with group I metals. Support this statement by giving some evidences.
11.27. In some of the reactions thallium resembles aluminium, whereas in others it resembles with group I metals. Support this statement by giving some evidences.
Tl belongs to group 13 and shows both the oxidation state +1 and +3 due to inert pair effect. Tl forms basic oxide like group I elements. TlO2 is strongly basic.
Upvote