Question 1

Question 2Give a chemical test to distinguish between :(a)	Sodium chloride soln. and sodium nitrate soln.(b) Hydrogen chloride gas and hydrogen sulphide gas.(c) Calcium nitrate soln. and zinc nitrate soln.(d) Carbon dioxide gas and sulphur dioxide gas.(e)	Sodium carbonate and sodium sulphite(f) Ferrous nitrate and lead nitrate.(g) Manganese dioxide and copper (Il) oxide.(h) Sodium nitrate and sodium sulphite [using dilute sulphuric acid].(i)	Sodium chloride and sodium sulphide(j) Sodium hydroxide solution and ammonium hydroxide solution.(k) Ammonium sulphate and sodium sulphate.(l)	Sulphuric acid from nitric acid and hydrochloric acid.(m) Magnesium chloride and magnesium nitrate solution(n) Zinc sulphate solution and zinc chloride solution(o) Iron (II) chloride soln. and iron (III) chloride soln.(p) Calcium nitrate soln. and calcium chloride soln.

Accepted Answer

(a) Add silver nitrate soln. to the given solns., sodium chloride reacts to form a white ppt. which is soluble in NH4OH and insoluble in dil. HNO3. The other soln. is sodium nitrate.NaCl + AgNO3 ⟶ AgCl ↓ [white ppt.] + NaNO3NaNO3 + AgNO3 ⟶ no white ppt.(b) Hydrogen sulphide gas turns moist lead acetate paper silvery black or black whereas, no change is observed in case of HCl gas.Pb(CH3COO)2 [colourless] + H2S ⟶ PbS [black] + 2CH3COOH(c) When NaOH is added to the given soln., Zn(NO3)2 reacts to form a gelatinous white ppt. which dissolves in excess of NaOH whereas, Ca(NO3)2 forms a milky white ppt. which is insoluble in excess of NaOH. Hence, the two can be distinguished.(d) Carbon dioxide gas has no effect on acidified potassium permanganate (KMnO4) and acidified potassium dichromate (K2Cr2O7) solution whereas sulphur dioxide gas turns acidified potassium permanganate from pink to clear colourless and acidified potassium dichromate from orange to clear green.2KMnO4 + 2H2O + 5SO2 ⟶ K2SO4 + 2MnSO4 + 2H2SO4K2Cr2O7 + H2SO4 + 3SO2 ⟶ K2SO4 + Cr2(SO4)3 + H2O(e) When dil. sulphuric acid is added to sodium carbonate and heated, colourless, odourless gas is evolved which turns lime water milky and has no effect on KMnO4 or K2Cr2O7 solutions.When dil. sulphuric acid is added to sodium sulphite and heated, colourless gas with suffocating odour is evolved which turns lime water milky. It turns acidified K2Cr2O7 from orange to clear green and pink coloured KMnO4 to clear colourless.Hence, the two compounds can be distinguished.(f) When NaOH is added to each of the compounds, a dirty green precipitate of Iron [II] hydroxide [Fe(OH)2] is formed in case of Ferrous nitrate whereas a chalky white precipitate of lead hydroxide [Pb(OH)2] is formed in case of lead nitrate. Iron [II] Hydroxide [Fe(OH)2] is insoluble in excess of NaOH, whereas Lead Hydroxide [Pb(OH)2] is soluble in excess of NaOH. Hence, the two compounds can be distinguished.(g) When each of the compound is heated with conc. hydrochloric acid, greenish yellow (chlorine) gas is evolved in case of manganese dioxide and filtrate is brownish in colour whereas, no chlorine gas is evolved in case of copper (II) oxide and filtrate is bluish in colour.MnO2 + 4HCl ⟶ MnCl2 + 2H2O + Cl2CuO + 2HCl ⟶ CuCl2 + H2O(h) Sodium nitrate will not react with dilute sulphuric acid.Sodium sulphite reacts with dil. sulphuric acid and colourless gas with suffocating odour is evolved which turns lime water milky.(i) When dil. sulphuric acid is added to sodium sulphide and heated, hydrogen sulphide gas is evolved which has the smell of rotten eggs and turns lead acetate paper black.Whereas, when conc. sulphuric acid is added to sodium chloride and heated, HCl gas is evolved which gives dense white fumes when a glass rod dipped in ammonia is brought near it.(j) When ammonium hydroxide is reacted with a solution of copper sulphate, a pale blue ppt. of copper hydroxide is formed which dissolves in excess of ammonium hydroxide forming a deep blue solution of a soluble complex salt [Cu(NH3)4]SO4 [tetramine copper [II] sulphate] .CuSO4 + 2NH4OH ⟶ (NH4)2SO4 + Cu(OH)2 ↓Cu(OH)2 + (NH4)2SO4 + 2NH4OH ⟶ [Cu(NH3)4]SO4 + 4H2OWhereas, when copper sulphate is added to sodium hydroxide solution, pale blue ppt. of copper hydroxide is obtained which is insoluble in excess of sodium hydroxide.CuSO4 + 2NaOH ⟶ Na2SO4 + Cu(OH)2 ↓(k) When ammonium sulphate is heated with NaOH, ammonia gas is produced which turns red litmus blue whereas, sodium sulphate does not react with sodium hydroxide.(NH4)2SO4 + 2NaOH ⟶ Na2SO4 + 2H2O + 2NH3Na2SO4 + NaOH ⟶ no reaction.(l) Barium chloride reacts with dil H2SO4 to form a white ppt. of barium sulphate.BaCl2 + H2SO4 [dil.] ⟶ 2HCl + BaSO4 ↓ [white ppt.]Whereas, HCl and nitric acid does not form a white ppt.BaCl2 + HCl ⟶ No white ppt.BaCl2 + HNO3 ⟶ No white ppt(m) Add silver nitrate solution to the given solns., magnesium chloride reacts to form a white ppt of silver chloride (AgCl). Whereas, magnesium nitrate show no reaction with silver nitrate. Hence, they can be distinguished using silver nitrate.MgCl2 + 2AgNO3 ⟶ 2AgCl↓ + Mg(NO3)2(n) When BaCl2 soln. is added to ZnSO4, a white ppt. of BaSO4 is formed, whereas, no ppt. is formed in case of ZnCl2. Hence, the two solns. can be distinguished.BaCl2 + ZnSO4 ⟶ BaSO4 ↓ [white ppt.] + ZnCl2BaCl2 + ZnCl2 ⟶ No white ppt.(o) When NaOH soln. is added to the given solns., FeCl2 reacts to form a dirty green ppt. of Fe(OH)2 whereas, FeCl3 reacts to form a reddish brown ppt. of Fe(OH)3.(p) Add silver nitrate soln. to the given solns., calcium chloride reacts to form a white ppt. which is soluble in NH4OH and insoluble in dil. HNO3. The other soln. is calcium nitrate.CaCl2 + 2AgNO3 ⟶ 2AgCl ↓ [white ppt.] + Ca(NO3)2Ca(NO3)2 + AgNO3 ⟶ no white ppt.

Question 2

Question 4Aqueous lead (II) nitrate can be distinguished from aqueous zinc nitrate by adding any of the following solution in excess, except:aqueous potassium chlorideaqueous sodium sulphatedilute sulphuric acidsodium hydroxide solution

Accepted Answer

sodium hydroxide solutionReason — Let's analyze each option:Aqueous potassium chloride: This will precipitate lead(II) chloride (PbCl₂) from lead (II) nitrate, whereas zinc chloride is soluble. Thus, this can distinguish between them, as lead will form a precipitate while zinc will not.Aqueous sodium sulphate: This will precipitate lead (II) sulphate (PbSO₄) from lead (II) nitrate since PbSO₄ is poorly soluble, while zinc sulphate is soluble. Thus, this can also distinguish between them.Dilute sulphuric acid: Similar to aqueous sodium sulphate, adding dilute H₂SO₄ will precipitate lead (II) sulphate from lead (II) nitrate but not zinc sulphate from zinc nitrate. So, this can distinguish between them.Sodium hydroxide solution: When added to both solutions in excess, this will not distinguish them because both lead (II) hydroxide and zinc hydroxide will initially precipitate but then both dissolve upon further addition of NaOH. Lead hydroxide forms a plumbate ion, and zinc hydroxide forms a zincate ion, both of which are soluble.

Question 3

Question 11Assertion (A): On passing H2S through lead nitrate solution, a black precipitate is formed.Reason (R): Lead nitrate reacts with H2S to form a black precipitate of PbS.Both A and R are true and R is the correct explanation of A.Both A and R are true but R is not the correct explanation of A.A is true but R is false.A is false but R is true.

Accepted Answer

Both A and R are true and R is the correct explanation of A.Explanation— H2S is colourless gas having a foul smell of rotten eggs. When H2S is passed through lead nitrate solution, a black precipitate of PbS is formed.Pb(NO3)2 + H2S ⟶ PbS ↓ + 2HNO3Hence, both assertion (A) and reason (R) are true and reason (R) is the correct explanation of assertion (A).

Question 4

Question 13Assertion (A): If barium nitrate solution is added to sodium sulphate solution, a white precipitate is formed.Reason (R): Sodium sulphate solution is white in colour.Both A and R are true and R is the correct explanation of A.Both A and R are true but R is not the correct explanation of A.A is true but R is false.A is false but R is true.

Accepted Answer

A is true but R is false.Explanation— When barium nitrate solution is added to sodium sulphate salt solution, white precipitate which is insoluble in water is formed. White precipitate is soluble in dil. HCl. Hence, the assertion (A) is true.Sodium sulphate solution is a colourless solution. Hence, the reason (R) is false.

Question 5

Question 5Salts A, B, C, D and E undergo reactions (i) to (v) respectively. Identify the anion present in these salts on the basis of these reactions.(a)	When silver nitrate solution is added to a solution of A, a white precipitate, insoluble in dilute nitric acid, is formed.(b)	Addition of dilute hydrochloric acid to B produces a gas which turns lead acetate paper black.(c)	When a freshly prepared solution of ferrous sulphate is added to a solution of C and concentrated sulphuric acid is gently poured from the side of the test-tube, a brown ring is formed.(d) When dilute sulphuric acid is added to D, a gas is produced which turns acidified potassium dichromate solution from orange to green.(e) Addition of dilute hydrochloric acid to E produces an effervescence. The gas produced turns lime water milky but does not affect acidified potassium dichromate solution.

Accepted Answer

(a) Chloride ion (Cl-)(b) Sulphide ion (S2-)(c) Nitrate (NO3-)(d) Sulphite ion (SO32-)(e) Carbonate ion (CO32-)

Question 6

Question 6State your observations when:(a)	lead nitrate solution and sodium chloride solution are mixed.(b)	zinc chloride solution, zinc nitrate solution and zinc sulphate solutions are added individually to(i)	barium chloride solution,(ii) lead nitrate solution.(c)	Decomposition of bicarbonates by dil. H2SO42NaHCO3 + H2SO4 ⟶ Na2SO4 + 2H2O + 2CO22KHCO3 + H2SO4 ⟶ K2SO4 + 2H2O + 2CO2(d) Zinc carbonate is heated strongly.(e)	a piece of moist blue litmus paper is introduced in a jar of chlorine.(f) paper soaked in potassium permanganate solution — is introduced in each case into a jar of sulphur dioxide.(g) When moist starch iodide paper is introduced into chlorine gas.

Accepted Answer

(a) When lead nitrate solution is mixed with sodium chloride solution, a white precipitate of lead chloride is seen and the soluble salt sodium nitrate is formed.2NaCl + Pb(NO3)2 ⟶ 2Na(NO3)2 + PbCl2↓Precipitate of lead chloride and sodium nitrate are formed.(b)    Zinc Chloride SolutionZinc Nitrate SolutionZinc Sulphate SolutionBarium Chloride SolutionNo reactionNo ppt. observedWhite ppt. is obtained which is insoluble in mineral acid.Lead Nitrate SolutionWhite ppt. is obtainedNo reactionNo ppt. observed(c) Carbon dioxide gas is evolved with brisk effervescence which turns blue litmus red and extinguishes a burning wooden splinter.(d) When zinc carbonate is strongly heated, the light amorphous white solid, changes to pale yellow colour.ZnCO3 →Δ\xrightarrow{\Delta}Δ​ ZnO + CO2(e) Moist blue litmus turns red and then may eventually get bleached.(f) Sulphur dioxide turns potassium permanganate from pink to clear colourless.2KMnO4 + 2H2O + 5SO2 ⟶ K2SO4 + 2MnSO4 + 2H2SO4(g) Chlorine gas turns moist starch iodide paper blue black.Cl2 + 2KI ⟶ 2KCl + I2[Starch + I2 ⟶ blue black colour]

Question 7

Question 7Complete the following table and write your observations.  Hydrogen sulphideAmmoniaSulphur dioxideHydrogen chlorideShake the gas with red litmus solution        Shake the gas with blue litmus solution        Apply a burning splint to the gas

Accepted Answer

Hydrogen sulphideAmmoniaSulphur dioxideHydrogen chlorideShake the gas with red litmus solutionNo changeRed litmus becomes blueNo changeNo changeShake the gas with blue litmus solutionBlue litmus becomes redNo changeBlue litmus becomes redBlue litmus becomes redApply a burning splint to the gasBurning splint is extinguishedBurning splint is extinguishedBurning splint is extinguishedBurning splint is extinguished

Question 8

Question 9State giving reasons if:(a) zinc and aluminium can be distinguished by heating the metal powder with concentrated sodium hydroxide solution.(b) calcium nitrate and lead nitrate can be distinguished by adding ammonium hydroxide solution to the salt solution.

Accepted Answer

(a) Zinc and aluminium cannot be distinguished by heating the metal powder with concentrated sodium hydroxide solution as they both react with conc. alkalis to form soluble sodium salts and hydrogen gas.Zinc reacts to form sodium zincateZn + 2NaOH ⟶ H2 + Na2ZnO2 [sodium zincate]Aluminium reacts to form sodium aluminate2Al + 2NaOH + 2H2O ⟶ 3H2 + 2NaAlO2 [sodium aluminate](b) Yes, calcium nitrate and lead nitrate can be distinguished using ammonium hydroxide solution. Ammonium hydroxide on reaction with lead nitrate gives chalky white precipitate of Pb(OH)2. No precipitation occurs on adding Ammonium hydroxide to calcium nitrate even when it is added in excess.Pb(NO3)2 + 2NH4OH ⟶ Pb(OH)2 + 2NH4NO3

Question 9

Question 10Identify the substance 'R' based on the information given below :The pale green solid 'R' turns reddish brown on heating. Its aqueous solution gives a white precipitate with barium chloride solution. The precipitate is insoluble in mineral acids.

Accepted Answer

The substance 'R' is Ferrous sulphate (FeSO4.7H2O). When heated strongly, the hydrous pale green ferrous sulphate (FeSO4.7H2O), loses it's water of crystallization and decomposes to form brown ferric oxide Fe2O3 along with sulphur dioxide (SO2) and sulphur trioxide (SO3).FeSO4.7H2O →Δ\xrightarrow{\Delta}Δ​ FeSO4 + 7H2O2FeSO4 →Δ\xrightarrow{\Delta}Δ​ Fe2O3 + SO2 + SO3Ferrous sulphate on reaction with barium chloride soln., forms a white ppt. of barium sulphate (BaSO4) which is insoluble in mineral acids.

Question 10

Question 8Mention the colour changes observed when following indicators are added:SolutionAcidsAlkalies(a)	Alkaline phenolphthalein solution,  (b)	Methyl orange solution,  (c) Neutral litmus solution

Accepted Answer

SolutionAcidsAlkalies(a)	Alkaline phenolphthalein solution,ColourlessPink(b)	Methyl orange solutionPinkYellow(c) Neutral litmus solutionRedBlue

Question 11

Question 12A student was asked to perform two experiments in the laboratory based on the instructions given:Observe the picture given below and state one observation for each of the Experiments 1 and 2 that you would notice on mixing the given solutions.(a) Experiment 1(b) Experiment 2

Accepted Answer

(a) White precipitate of barium sulphate is formed.Reason — When a solution of zinc sulphate is added to a solution of barium chloride, a double displacement reaction occurs. This reaction involves the exchange of ions between the two compounds and a white precipitate of barium sulphate is formed.ZnSO4 (aq) + BaCl2 (aq) ⟶ BaSO4 (s) + ZnCl2 (aq).(b) Blue precipitate dissolves to form an inky blue/deep blue solution.Reason — The light blue precipitate of copper(II) hydroxide (Cu(OH)2) dissolves in excess of ammonium hydroxide due to the formation of a deep blue complex, tetraamminecopper(II) ([Cu(NH3)4]2+), making it soluble.

Question 12

Question 1(a) Give only one suitable chemical test to identify the following gases.(i) Ammonia(ii) Sulphur dioxide(iii) Hydrogen chloride(iv) Chlorine(v) Carbon dioxide(vi) Oxygen(vii) Hydrogen(b) Select a basic gas mentioned in Q. 1(a). How is the basic nature suspected?(c) Select acidic gases from the gases mentioned in Q. 1 (a). How is the acidic nature suspected?(d) The two gases A and B are bleaching agents. A is greenish yellow and bleaches due to it's oxidising property while B a colourless gas bleaches due to reduction. Identify A and B.(e) Which gas turns blue cobalt chloride paper light pink?Give one similarity in test between (i) Cl2 and HCl (ii) SO2 and CO2.

Accepted Answer

(i) Ammonia — When a glass rod dipped in conc. HCl is brought near the gas, dense white fumes of ammonium chloride are formed.(ii) Sulphur dioxide — Sulphur dioxide gas turns acidified potassium permanganate from pink to clear colourless and acidified potassium dichromate from orange to clear green.(iii) Hydrogen chloride — Forms a curdy white ppt. on passage through AgNO3 solution. The precipitate dissolves in excess of NH4OH.(iv) Chlorine — Chlorine turns moist blue litmus red and then bleaches it.(v) Oxygen — Oxygen gas rekindles a glowing wooden splinter.(iv) Hydrogen — Hydrogen gas burns with a 'pop' sound in air.(b) Ammonia is a basic gas. It turns red litmus blue.(c) Sulphur dioxide, Hydrogen chloride, Chlorine, Carbon dioxide.(d) A is Chlorine and B is Sulphur dioxide.(e) Water vapour(i) Similarity in test of Cl2 and HCl — Forms a white ppt. on reaction with AgNO3 solution.(ii) Similarity in test of SO2 and CO2 — Both turn lime water milky.

Question 13

Question 3Name:(a)	Two carbonates which do not produce carbon dioxide on heating.(b)	A colourless gas which bleaches(c)	Gases which have sour taste(d) Greenish yellow gas which also bleaches(e) Gas with rotten egg smell.

Accepted Answer

(a)	Sodium carbonate [Na2CO3] and potassium carbonate [K2CO3](b) Sulphur dioxide [SO2](c) Carbon dioxide [CO2](d) Chlorine [Cl2](e) Hydrogen sulphide [H2S]

Practical Work

Exercise 13 Long Answer Type

Exercise 13 Multiple Choice Type

Exercise 13 Short Answer Type

Exercise 13 Very Short Answer Type

Intext Questions