1 - (a) Blue (b) Red (c) Hydrogen gas (d) Basic , Alkaline (e) Solid
2 - (a) Sodium Sulphate [Na₂SO₄] is prepared by neutralising NaOH and H₂SO₄ .
(b) Lead carbonate [PbCO₃] is prepared by precipitation .
(c) Copper sulphate [ CuSO₄. 5H₂O] , by the action of acid on metal oxide .
(d) Zinc sulphate [ZnS] by direct combination .
3 - Value of pH can be increased by addition of some alkaline substance or a basic substance .
Value of pH can be decreased by adding some acid or acidic substance .
4 - (a) Solution P having pH value 13 will liberate ammonia gas from ammonium sulphate , because strong base can liberate ammonia from ammonium suphate solution.
(b) Solution R is a strong acid , as strong acid has pH lower than 7.
(c) Solution Q , as its pH is 6 and hence a weak acid , contains both molecules as well as ions.
5 - (a) Water of crystallisation.
(b) Color of anhydrous CuSO₄ is white.
(c) By treating with concentrated H₂SO₄.
It absorbs water of crystallisation from hydrated salt.
(d) Anhydrous Calcium chloride [CaCl₂] is deliquescent substance.
6 - (a) NaHSO₄ (b) AgCl (c) CuSO₄ .5H₂O (d) CuCO₃ (e) Pb(NO₃)₂
7 - (a) No effect .
(b) Aqueous solution of MgCl₂ will turn blue litmus red .
8 - Solid anhydrous [FeCl₃] is deliquescent substance whichabsorbs moisture of air and then dissolves in absorbed moisture to change to liquid state . So FeCl₃is stored in air tight bottles .
9 - Zinc (Zn)
Zn(OH)₂ is soluble in NaOH .
Zn(OH)₂ ＋ 2NaOH → NaZnO₂ ＋ 2H₂O
10 - Sodium hydrogen sulphate → NaHSO₄
11 - (a) Pb(NO₃) ＋ 2NaCl → PbCl₂↓ ＋ 2NaNO₃
White precipitate of lead chloride is formed .
(b) Barium chloride when added to Zinc chloride solution - No reaction takes place
Barium chloride added to Zinc nitrate solution - No reaction takes place
Barium chloride added to Zinc sulphate solution - White precipitate formed
Lead nitrate solution is added to Zinc chloride solution - White precipitate is formed
Lead nitrate added to Zinc nitrate solution - No reaction takes place
Lead nitrate added to Zinc sulphate solution - White precipitate is formed .
12 - (a) Light green (b) Colorless (c) Blue (d) Colorless (e) Colorless
13 - (a) Zn (b) Zn(OH)₂ white gelatinous precipitate
14 - Add calcium salt Ca(NO₃)₂ colorless to both the bottles A and B . The bottle in which precipitate
(white in color) is seen is NaOH solution i.e. bottle B.
Hence bottle B contains NaOH solution bottle A - No white precipitate is observed contains NH₄OH solution .
15 - Add dilute HCl to both lead carbonate and Zinc carbonate in separate test tubes , Lead carbonate
does not produce CO₂ gas , whereas ZnCO₃ produces CO₂ gas which turns lime water milky.
16 - Sugarcane solution being a covalent compound does not dissociate into ions in solution and does not conduct electricity . Whereas Sodium chloride (NaCl) being ionic compound dissociates completely in solution and conduct electricity .
17 - Copper is more reactive than silver . Therefore , copper will displace silver from AgNO₃ to
produce Cu(NO₃)₂ .
18 - NaCl → Na⁺ ＋ Cl⁻
H₂O ⇌ H⁺ ＋ OH
H₂O ＋ H₂O ⇌ H₃O⁺ ＋ OH⁻
At cathode ; -
Na⁺ and H⁺ (H₃O⁺) migrate to cathode . But despite high concentration of Na⁺, H⁺ gains electron more easily than Na⁺ (also H⁺ being lower than Na⁺ in electrochemical series), So
Hydrogen is evolved at cathode.
H⁺ ＋ e⁻ → H
H ＋ H → H₂
19 - A solution of caustic soda (NaOH) in water or in fused state conducts an electric current because the dielectric effect of the polar water molecules overcome the force of electrostatic attraction between the ions and allow them mobility to conduct electricity . In the molten state (fused) , the high temperature required to melt the solid , weakness the bond between the particles and the ions are set free.
20 - (a) Electrolyte (b) Nickel (c) Cathode (d) Anode (e) Cations (f) Cathode , anode
21 - (a) X²⁺ Y³⁻
X - 2e⁻ → [X²⁺] cation
Y ＋ 3e⁻ → [Y³⁻] Anion
(b) X₃ Y₂
(c) Cathode , Anode
22 - Only Molecules
23 - (a) Because copper is an electronic conductor as it is a metal.
(b) Sodium chloride (an ionic solid) does not conduct electricity in its solid state . It is because
the anions (Cl⁻) and cations (Na⁺), remain in fact occupying fixed position in the crystal lattice due to strong electrostatic attractive forces among them . The ions , therefore are unable to move to any large extant when electric field is affected . hence no current.
24 - (a) Cu → Cu²⁺ ＋ 2e⁻ . This reaction takes place at anode . This is an example of oxidation.
(b) Cu²⁺ (Copper ions will get discharged at cathode )
Note - An ion present lower in the electrochemical series gets discharged at the relevant electrode in preference to ions above it .
Cu²⁺ ＋ 2e⁻ → Cu (s)
(Copper is deficient in e⁻ , it will accept two electrons and get deposited at cathode)
(c) Carbon tetrachloride is a non-electrolyte because it is a covalent compound , it does not ionise and hence does not conduct electricity.
25 - (a) It is a complex salt .
(b) Silver nitrate is not used as an electrolyte since deposition of silver is rapid and the coating
is not uniform. Hence sodium argentocyanide is used.
(c) A direct current of smaller magnitude should be applied for a long time.
Dissociation Reaction -
Na[Ag(CN)₂] ⇌ Na⁺ ＋ Ag⁺ ＋ 2CN⁻
cations →↓cathode
Both Na⁺and Ag⁺ will migrate towards cathode but Ag⁺ ions will be discharged.
(d) Reaction at cathode -
Ag⁺ ＋ e⁻ → Ag
(e) Reaction at anode -
The silver atoms from the anode lose electrons and other into the solution as silver ions.
Ag - 1e⁻ → Ag⁺ ( sodium ions released in solution )
26 - `Lead (II) bromide
27 - Cell A ; Strong electrolyte (NaCl) → Bulb glows brightly
Cell B : Weak Electrolyte (acetic acid) → Bulb glows dimly
Cell C : Non electrolyte (sugar solution) → Bulb does not glow
28 - Alkali metals are very reactive and react readily with oxygen , moisture of air and with water and catch fire because of Hydrogen produce during reaction . Hence Alkali metals are kept in
kerosene oil.
29 - (a) Metal A (2, 8 , 1) and Metal B(2, 8 , 8, 2)lie in the same period IIIrd . Metal A is more reactive , because on moving from left to right in a period metallic nature decreases due to in
increase in atomic number , nuclear pull increases , there by size decreases.
Metal A is sodium (Na)
Metal B is calcium (Ca)
2Na ＋ 2HCl (dil) → 2NaCl ＋ H₂
Ca ＋ 2HCl → CaCl₂ ＋ H₂
2Na ＋ H₂SO₄ → Na₂SO₄ ＋ H₂
Ca ＋ H₂SO₄ → CaSO₄ ＋ H₂↑
(b) (1) Oxides of Na and Ca are stable to heat.
(2) Hydroxides of sodium are stable to heat and are soluble in water .
Hydroxides of calcium decompose on heating to form metal oxide and water vapour.
(3) Carbonate of sodium is stable to heat and soluble in water.
Carbonate of calcium decomposes on heating to form metal oxide.
(4) Nitrates of sodium on heating forms sodium nitrate and oxygen .
Nitrates of calcium on heating forms NO₂ and O₂
30 - Corrosion of metal is responsible for these coatings.
Black coating on silver is tarnishing of silver and pollutant (H₂S) forms black coating (Ag₂S)
Green coating on Copper is basic copper (II)sulphate [3Cu(OH)₂. CuSO₄]
31 -Metals at the top of reactivity series i.e. Potassium , sodium , calcium , magnesium and
aluminium have great affinity for oxygen , cannot be reduced by carbon or carbon monoxide
or hydrogen .
Metal in the middle of activity series (iron , zinc , lead and copper) are moderately reactive and
not found in oxide form. These are found in nature as sulphides or carbonate . These are first
converted into oxides and can be reduced by carbon or CO or H₂.
ZnO ＋ C(s) → Zn ＋ CO
PbO ＋ CO → Pb ＋ CO₂
CuO ＋ H₂ → Cu ＋ H₂O
Metals low in the activity series are very less reactive . Oxides of these metals are reduced to
metals by heating alone.
2Ag₂O → 4Ag ＋ O₂ ( at temperature above 300⁰C
32 - In air aluminium gets oxidised and forms a thin protective layer on its surface , which protects
further corrosion .
33 - Aluminium vessels should not be cleaned with powders containing alkalis as it reacts with alkalis .
2Al ＋ 2NaOH ＋ H₂O → 2NaAlO₂ ＋ 3H₂
34 - The metal aluminium is not attacked by dilute or strong nitric acid . It renders ALUMINIUM PASSIVE due to the formation of an oxide film on its surface.
35 - (a) Copper (b) Iron (c) Zinc (d) Magnesium
36 - (a) Chlorine
The compound formed which is strongly acidic in water is HCl.
H₂ ＋ Cl₂ → 2HCl
37 - A dilute aqueous aqueous solution of hydrochloric acid gets gradually concentration on distillation , till the concentration of the acid reaches 22.2% HCl by weight which boils at 110⁰c
When this concentration is reached , no further increase in concentration of the acids becomes possible by boiling (constant boiling , mixture , or azeotroope ).
Reason → Vapours evolved before 110⁰c are vapours of water but a temperature above 110⁰c
vapours consists mostly of molecules of HCl .
38 - (a) CuO (s) Copper (II) oxide
CuO ＋ 2HCl → CuCl₂ ＋ H₂O
(black) (blue green)
39 - A is AgNO₃ ( Silver Nitrate)
B is HCl ( Hydrochloric acid)
C is AgCl ( Silver Chloride)
40 - A is (NH₄Cl) Ammonium chloride . B is (NH₃) Ammonia gas
2NH₄Cl ＋ Ca(OH)₂ → CaCl₂ (s) ＋ 2H₂O ＋ 2NH₃↑
(Ammonium chloride - slaked lime )
41 - (a) Name of the gas P is Ammonia .
(b) NH₃
(c) (I) It is used in Ice factory
(II) In the manufacture of nitric acid .
(III) In the manufacture of Nylon and Rayon.
42 - NH₃ ＋ H₂O ⇌ NH₄OH
CuSO₄ ＋ 2NH₄OH → [NH₄SO₄ ＋ Cu(OH)₂↓
(pale blue precipitate)
The pale blue precipitate of copper hydrogen dissolves in excess of Ammonium hydroxide
forming an AZURE BLUE (deep blue) soluble complex salt [ Tetra amine copper II] sulphate]
[Cu(NH₃)₄]SO₄ is forme
Cu(OH)₂ ＋ (NH₃)₂SO₄ ＋ 2NH₄OH → [Cu(NH₃)₄]SO₄ ＋ 4H₂O
(pale blue ppt.) (Tetra amine copper II sulphate)
43 - The gas A is Ammonia (NH₃)
The gas B is Oxygen (O₂)
Catalyst → Pt
Colorless gas C obtained → NO (nitric oxide)
With air NO forms NO₂ (brown gas) → Gas D
4NH₃ ＋ 5H₂O → 4NO↑ ＋ 6H₂O ＋ ⧍
2NO ＋ O₂ → 2NO₂
(brown gas)
Solution of NH₃ in water NH₄OH turns Red litmus Blue
NH₃ ＋ H₂O → NH₄OH
44 - In the preparation of Nitric acid from KNO₃ concentrated hydrochloric acid is not used in place
of concentrated sulphuric acid because hyrdochloric acid is volatile and hence nitric acid vapours
will carry hydrochloric acid vapours .
45 - Nitric acid forms a constant boiling mixture with water containing 68% acid . This mixture boils
constantly at the constant boiling point without any change in its composition . At this temperature , the gas and the water vapour escape together . Hence the composition of the solution remains unchanged . That is why nitric acid can't be concentrated beyond 68% by the
distillation of dilute solution of HNO₃ .
46 - Iron when treated with concentrated pure Nitric acid become Passive (inert) due to the formation of thin layer of insoluble metallic oxide . which stops the reaction .
47 - (a) A → Blue crystalline solid is Cu[NO₃]₂
B → reddish brown gas is NO₂
C → gas with smell of rotten egg is H₂S
(b) 2Cu[NO₃]₂ → 2CuO ＋ 4NO₂ ＋ O₂
blue crystalline black
(c) Cu[NO₃]₂ ＋ H₂S → CuS ＋ 2HNO₃
black ppt.
48 - Because the nitric acid produced reacts with almost all the materials including cork and rubber
Glass is only exception .Pure nitric acid is unstable to sunlight.
4HNO₃ → 4NO₂ ＋ 2H₂O ＋ O₂
sun light
49 - HNO₃ (nitric acid)
50 - A piece of wood becomes black , because carbon is set free when cellulose [C₆H₁₀O₅]ₙ gets
charred by concentrated H₂SO₄ .
51 - Brisk effervescence is seen due to the evolution of carbon dioxide when H₂SO₄ is added to sodium carbonate .
Na₂CO₃ ＋ H₂SO₄ → Na₂SO₄ ＋ H₂O ＋ CO₂↑
52 - Melting point and boiling point increases with increase in molecular weight .
53 - Pure acetic acid is called glacial acetic acid because below 16.5⁰c it solidify as icy mass .
54 - The gas A is Chlorine (Cl₂)
The gas B is sulphuric dioxide (SO₂)
55 - (a) Compound A is NaCl and anion is [Cl⁻]
(b) Compound B is H₂SO₄ and anion is [SO₄²⁻]
(c) Compound C is PbCO₃ and anion is [CO₃²⁻]
(d) compound D is Na₂SO₃ and anion is [SO₃²⁻]
56 - Calcium ions [Ca²⁺]
57 - In solution B cation is [Cu²⁺] . color of B is Blue.
58 - Three tests to identify Ammonia gas are :
(I) has sharp characteristic odour .
(II) It gives dense white fumes with conc. HCl
(II) It gives light to keep brown color or precipitate with Nesseler's solution K₂HgI₄
59 - (a) A is NH₄Cl Ammonium chloride
(b) B is Calcium hydroxide Ca(OH)₂
(c) C is CaO
(d) D is Ca (calcium)
(e) E is Copper II nitrate , F is CuO copper oxide
(f) E is Cu[NO₃] . F is CuO
(g) H is Cl₂ (chlorine) . I is HCl
(h) H is Hcl and B is calcium hydroxide.
60 - (a) D and E
(b) B and E
(c) D
(d) A
(e) D lead nitrate
61 - (a) Iron (II) chloride
(b) Lead (II) chloride
(c) Nitroso Iron (II) sulphate
(d) Sodium chloride
(e) Chromium sulphate.
2 - (a) Sodium Sulphate [Na₂SO₄] is prepared by neutralising NaOH and H₂SO₄ .
(b) Lead carbonate [PbCO₃] is prepared by precipitation .
(c) Copper sulphate [ CuSO₄. 5H₂O] , by the action of acid on metal oxide .
(d) Zinc sulphate [ZnS] by direct combination .
3 - Value of pH can be increased by addition of some alkaline substance or a basic substance .
Value of pH can be decreased by adding some acid or acidic substance .
4 - (a) Solution P having pH value 13 will liberate ammonia gas from ammonium sulphate , because strong base can liberate ammonia from ammonium suphate solution.
(b) Solution R is a strong acid , as strong acid has pH lower than 7.
(c) Solution Q , as its pH is 6 and hence a weak acid , contains both molecules as well as ions.
5 - (a) Water of crystallisation.
(b) Color of anhydrous CuSO₄ is white.
(c) By treating with concentrated H₂SO₄.
It absorbs water of crystallisation from hydrated salt.
(d) Anhydrous Calcium chloride [CaCl₂] is deliquescent substance.
6 - (a) NaHSO₄ (b) AgCl (c) CuSO₄ .5H₂O (d) CuCO₃ (e) Pb(NO₃)₂
7 - (a) No effect .
(b) Aqueous solution of MgCl₂ will turn blue litmus red .
8 - Solid anhydrous [FeCl₃] is deliquescent substance whichabsorbs moisture of air and then dissolves in absorbed moisture to change to liquid state . So FeCl₃is stored in air tight bottles .
9 - Zinc (Zn)
Zn(OH)₂ is soluble in NaOH .
Zn(OH)₂ ＋ 2NaOH → NaZnO₂ ＋ 2H₂O
10 - Sodium hydrogen sulphate → NaHSO₄
11 - (a) Pb(NO₃) ＋ 2NaCl → PbCl₂↓ ＋ 2NaNO₃
White precipitate of lead chloride is formed .
(b) Barium chloride when added to Zinc chloride solution - No reaction takes place
Barium chloride added to Zinc nitrate solution - No reaction takes place
Barium chloride added to Zinc sulphate solution - White precipitate formed
Lead nitrate solution is added to Zinc chloride solution - White precipitate is formed
Lead nitrate added to Zinc nitrate solution - No reaction takes place
Lead nitrate added to Zinc sulphate solution - White precipitate is formed .
12 - (a) Light green (b) Colorless (c) Blue (d) Colorless (e) Colorless
13 - (a) Zn (b) Zn(OH)₂ white gelatinous precipitate
14 - Add calcium salt Ca(NO₃)₂ colorless to both the bottles A and B . The bottle in which precipitate
(white in color) is seen is NaOH solution i.e. bottle B.
Hence bottle B contains NaOH solution bottle A - No white precipitate is observed contains NH₄OH solution .
15 - Add dilute HCl to both lead carbonate and Zinc carbonate in separate test tubes , Lead carbonate
does not produce CO₂ gas , whereas ZnCO₃ produces CO₂ gas which turns lime water milky.
16 - Sugarcane solution being a covalent compound does not dissociate into ions in solution and does not conduct electricity . Whereas Sodium chloride (NaCl) being ionic compound dissociates completely in solution and conduct electricity .
17 - Copper is more reactive than silver . Therefore , copper will displace silver from AgNO₃ to
produce Cu(NO₃)₂ .
18 - NaCl → Na⁺ ＋ Cl⁻
H₂O ⇌ H⁺ ＋ OH
H₂O ＋ H₂O ⇌ H₃O⁺ ＋ OH⁻
At cathode ; -
Na⁺ and H⁺ (H₃O⁺) migrate to cathode . But despite high concentration of Na⁺, H⁺ gains electron more easily than Na⁺ (also H⁺ being lower than Na⁺ in electrochemical series), So
Hydrogen is evolved at cathode.
H⁺ ＋ e⁻ → H
H ＋ H → H₂
19 - A solution of caustic soda (NaOH) in water or in fused state conducts an electric current because the dielectric effect of the polar water molecules overcome the force of electrostatic attraction between the ions and allow them mobility to conduct electricity . In the molten state (fused) , the high temperature required to melt the solid , weakness the bond between the particles and the ions are set free.
20 - (a) Electrolyte (b) Nickel (c) Cathode (d) Anode (e) Cations (f) Cathode , anode
21 - (a) X²⁺ Y³⁻
X - 2e⁻ → [X²⁺] cation
Y ＋ 3e⁻ → [Y³⁻] Anion
(b) X₃ Y₂
(c) Cathode , Anode
22 - Only Molecules
23 - (a) Because copper is an electronic conductor as it is a metal.
(b) Sodium chloride (an ionic solid) does not conduct electricity in its solid state . It is because
the anions (Cl⁻) and cations (Na⁺), remain in fact occupying fixed position in the crystal lattice due to strong electrostatic attractive forces among them . The ions , therefore are unable to move to any large extant when electric field is affected . hence no current.
24 - (a) Cu → Cu²⁺ ＋ 2e⁻ . This reaction takes place at anode . This is an example of oxidation.
(b) Cu²⁺ (Copper ions will get discharged at cathode )
Note - An ion present lower in the electrochemical series gets discharged at the relevant electrode in preference to ions above it .
Cu²⁺ ＋ 2e⁻ → Cu (s)
(Copper is deficient in e⁻ , it will accept two electrons and get deposited at cathode)
(c) Carbon tetrachloride is a non-electrolyte because it is a covalent compound , it does not ionise and hence does not conduct electricity.
25 - (a) It is a complex salt .
(b) Silver nitrate is not used as an electrolyte since deposition of silver is rapid and the coating
is not uniform. Hence sodium argentocyanide is used.
(c) A direct current of smaller magnitude should be applied for a long time.
Dissociation Reaction -
Na[Ag(CN)₂] ⇌ Na⁺ ＋ Ag⁺ ＋ 2CN⁻
cations →↓cathode
Both Na⁺and Ag⁺ will migrate towards cathode but Ag⁺ ions will be discharged.
(d) Reaction at cathode -
Ag⁺ ＋ e⁻ → Ag
(e) Reaction at anode -
The silver atoms from the anode lose electrons and other into the solution as silver ions.
Ag - 1e⁻ → Ag⁺ ( sodium ions released in solution )
26 - `Lead (II) bromide
27 - Cell A ; Strong electrolyte (NaCl) → Bulb glows brightly
Cell B : Weak Electrolyte (acetic acid) → Bulb glows dimly
Cell C : Non electrolyte (sugar solution) → Bulb does not glow
28 - Alkali metals are very reactive and react readily with oxygen , moisture of air and with water and catch fire because of Hydrogen produce during reaction . Hence Alkali metals are kept in
kerosene oil.
29 - (a) Metal A (2, 8 , 1) and Metal B(2, 8 , 8, 2)lie in the same period IIIrd . Metal A is more reactive , because on moving from left to right in a period metallic nature decreases due to in
increase in atomic number , nuclear pull increases , there by size decreases.
Metal A is sodium (Na)
Metal B is calcium (Ca)
2Na ＋ 2HCl (dil) → 2NaCl ＋ H₂
Ca ＋ 2HCl → CaCl₂ ＋ H₂
2Na ＋ H₂SO₄ → Na₂SO₄ ＋ H₂
Ca ＋ H₂SO₄ → CaSO₄ ＋ H₂↑
(b) (1) Oxides of Na and Ca are stable to heat.
(2) Hydroxides of sodium are stable to heat and are soluble in water .
Hydroxides of calcium decompose on heating to form metal oxide and water vapour.
(3) Carbonate of sodium is stable to heat and soluble in water.
Carbonate of calcium decomposes on heating to form metal oxide.
(4) Nitrates of sodium on heating forms sodium nitrate and oxygen .
Nitrates of calcium on heating forms NO₂ and O₂
30 - Corrosion of metal is responsible for these coatings.
Black coating on silver is tarnishing of silver and pollutant (H₂S) forms black coating (Ag₂S)
Green coating on Copper is basic copper (II)sulphate [3Cu(OH)₂. CuSO₄]
31 -Metals at the top of reactivity series i.e. Potassium , sodium , calcium , magnesium and
aluminium have great affinity for oxygen , cannot be reduced by carbon or carbon monoxide
or hydrogen .
Metal in the middle of activity series (iron , zinc , lead and copper) are moderately reactive and
not found in oxide form. These are found in nature as sulphides or carbonate . These are first
converted into oxides and can be reduced by carbon or CO or H₂.
ZnO ＋ C(s) → Zn ＋ CO
PbO ＋ CO → Pb ＋ CO₂
CuO ＋ H₂ → Cu ＋ H₂O
Metals low in the activity series are very less reactive . Oxides of these metals are reduced to
metals by heating alone.
2Ag₂O → 4Ag ＋ O₂ ( at temperature above 300⁰C
32 - In air aluminium gets oxidised and forms a thin protective layer on its surface , which protects
further corrosion .
33 - Aluminium vessels should not be cleaned with powders containing alkalis as it reacts with alkalis .
2Al ＋ 2NaOH ＋ H₂O → 2NaAlO₂ ＋ 3H₂
34 - The metal aluminium is not attacked by dilute or strong nitric acid . It renders ALUMINIUM PASSIVE due to the formation of an oxide film on its surface.
35 - (a) Copper (b) Iron (c) Zinc (d) Magnesium
36 - (a) Chlorine
The compound formed which is strongly acidic in water is HCl.
H₂ ＋ Cl₂ → 2HCl
37 - A dilute aqueous aqueous solution of hydrochloric acid gets gradually concentration on distillation , till the concentration of the acid reaches 22.2% HCl by weight which boils at 110⁰c
When this concentration is reached , no further increase in concentration of the acids becomes possible by boiling (constant boiling , mixture , or azeotroope ).
Reason → Vapours evolved before 110⁰c are vapours of water but a temperature above 110⁰c
vapours consists mostly of molecules of HCl .
38 - (a) CuO (s) Copper (II) oxide
CuO ＋ 2HCl → CuCl₂ ＋ H₂O
(black) (blue green)
39 - A is AgNO₃ ( Silver Nitrate)
B is HCl ( Hydrochloric acid)
C is AgCl ( Silver Chloride)
40 - A is (NH₄Cl) Ammonium chloride . B is (NH₃) Ammonia gas
2NH₄Cl ＋ Ca(OH)₂ → CaCl₂ (s) ＋ 2H₂O ＋ 2NH₃↑
(Ammonium chloride - slaked lime )
41 - (a) Name of the gas P is Ammonia .
(b) NH₃
(c) (I) It is used in Ice factory
(II) In the manufacture of nitric acid .
(III) In the manufacture of Nylon and Rayon.
42 - NH₃ ＋ H₂O ⇌ NH₄OH
CuSO₄ ＋ 2NH₄OH → [NH₄SO₄ ＋ Cu(OH)₂↓
(pale blue precipitate)
The pale blue precipitate of copper hydrogen dissolves in excess of Ammonium hydroxide
forming an AZURE BLUE (deep blue) soluble complex salt [ Tetra amine copper II] sulphate]
[Cu(NH₃)₄]SO₄ is forme
Cu(OH)₂ ＋ (NH₃)₂SO₄ ＋ 2NH₄OH → [Cu(NH₃)₄]SO₄ ＋ 4H₂O
(pale blue ppt.) (Tetra amine copper II sulphate)
43 - The gas A is Ammonia (NH₃)
The gas B is Oxygen (O₂)
Catalyst → Pt
Colorless gas C obtained → NO (nitric oxide)
With air NO forms NO₂ (brown gas) → Gas D
4NH₃ ＋ 5H₂O → 4NO↑ ＋ 6H₂O ＋ ⧍
2NO ＋ O₂ → 2NO₂
(brown gas)
Solution of NH₃ in water NH₄OH turns Red litmus Blue
NH₃ ＋ H₂O → NH₄OH
44 - In the preparation of Nitric acid from KNO₃ concentrated hydrochloric acid is not used in place
of concentrated sulphuric acid because hyrdochloric acid is volatile and hence nitric acid vapours
will carry hydrochloric acid vapours .
45 - Nitric acid forms a constant boiling mixture with water containing 68% acid . This mixture boils
constantly at the constant boiling point without any change in its composition . At this temperature , the gas and the water vapour escape together . Hence the composition of the solution remains unchanged . That is why nitric acid can't be concentrated beyond 68% by the
distillation of dilute solution of HNO₃ .
46 - Iron when treated with concentrated pure Nitric acid become Passive (inert) due to the formation of thin layer of insoluble metallic oxide . which stops the reaction .
47 - (a) A → Blue crystalline solid is Cu[NO₃]₂
B → reddish brown gas is NO₂
C → gas with smell of rotten egg is H₂S
(b) 2Cu[NO₃]₂ → 2CuO ＋ 4NO₂ ＋ O₂
blue crystalline black
(c) Cu[NO₃]₂ ＋ H₂S → CuS ＋ 2HNO₃
black ppt.
48 - Because the nitric acid produced reacts with almost all the materials including cork and rubber
Glass is only exception .Pure nitric acid is unstable to sunlight.
4HNO₃ → 4NO₂ ＋ 2H₂O ＋ O₂
sun light
49 - HNO₃ (nitric acid)
50 - A piece of wood becomes black , because carbon is set free when cellulose [C₆H₁₀O₅]ₙ gets
charred by concentrated H₂SO₄ .
51 - Brisk effervescence is seen due to the evolution of carbon dioxide when H₂SO₄ is added to sodium carbonate .
Na₂CO₃ ＋ H₂SO₄ → Na₂SO₄ ＋ H₂O ＋ CO₂↑
52 - Melting point and boiling point increases with increase in molecular weight .
53 - Pure acetic acid is called glacial acetic acid because below 16.5⁰c it solidify as icy mass .
54 - The gas A is Chlorine (Cl₂)
The gas B is sulphuric dioxide (SO₂)
55 - (a) Compound A is NaCl and anion is [Cl⁻]
(b) Compound B is H₂SO₄ and anion is [SO₄²⁻]
(c) Compound C is PbCO₃ and anion is [CO₃²⁻]
(d) compound D is Na₂SO₃ and anion is [SO₃²⁻]
56 - Calcium ions [Ca²⁺]
57 - In solution B cation is [Cu²⁺] . color of B is Blue.
58 - Three tests to identify Ammonia gas are :
(I) has sharp characteristic odour .
(II) It gives dense white fumes with conc. HCl
(II) It gives light to keep brown color or precipitate with Nesseler's solution K₂HgI₄
59 - (a) A is NH₄Cl Ammonium chloride
(b) B is Calcium hydroxide Ca(OH)₂
(c) C is CaO
(d) D is Ca (calcium)
(e) E is Copper II nitrate , F is CuO copper oxide
(f) E is Cu[NO₃] . F is CuO
(g) H is Cl₂ (chlorine) . I is HCl
(h) H is Hcl and B is calcium hydroxide.
60 - (a) D and E
(b) B and E
(c) D
(d) A
(e) D lead nitrate
61 - (a) Iron (II) chloride
(b) Lead (II) chloride
(c) Nitroso Iron (II) sulphate
(d) Sodium chloride
(e) Chromium sulphate.
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