BITSAT Chemistry Analytical Chemistry MCQs

a) FeSO₄. NO

b) [Fe(H₂O)₅NO]²⁺

c) [Fe(H₂O)₅NO]⁺

d) [Fe(H₂O)₅NO]³⁺

Answer: [Fe(H₂O)₅NO]²⁺

Question: Sometimes, the colour observed in Lassaigne’s test for nitrogen is green. It is because

a) Of green colour of ferrous sulphate

b) Ferric ferrocyanide is also green

c) Of green colour of copper sulphate

d) Of excess of Fe³⁺ ions whose yellow colour makes the blue colour of ferric ferrocyanide to appear green.

Answer: Of excess of Fe³⁺ ions whose yellow colour makes the blue colour of ferric ferrocyanide to appear green.

Question: Which of the following ions can be separated by aq. NH₄OH in presence of NH₄Cl

a) Al³⁺ and Fe³⁺

b) Cr³⁺ and Al³⁺

c) Cu²⁺ and Al³⁺

d) None of these

Answer: Cu²⁺ and Al³⁺

Question: 3.92 g of ferrous ammonium sulphate react completely with 50 ml 

KMnO₄ solution. The percentage purity of the sample is

a) 50

b) 78.4

c) 80

d) 39.2

Answer: 50

Question: A mixture of chlorides of copper, cadmium, chromium, iron and aluminium was dissolved in water acidified with HCl and hydrogen sulphide gas was passed for sufficient time. It was filtered, boiled and a few drops of nitric acid were added while boiling. To this solution ammonium chloride and sodium hydroxide were added and filtered. The filterate shall give test for.

a) Sodium and iron

b) Sodium and aluminium

c) Aluminium and iron

d) Sodium, iron, cadmium and Al

Answer: Sodium and aluminium

Question: Volume of 3% solution of sodium carbonate necessary to neutralise a litre of 0.1 N sulphuric acid

a) 176.66 ml

b) 156.6 ml

c) 116.0 ml

d) 196.1 ml

Answer: 176.66 ml

Question: 0.45 g of acid molecular weight 90 is neutralised by 20 ml of 0.5N caustic potash. The basicity of acid is

a) 1

b) 2

c) 3

d) 4

Answer: 2

Question: In the reaction of KMnO₄ with an oxalate in acidic medium,  is reduced to Mn2+ and  is oxidised to CO₂. Hence, 50 ml of 0.02M KMnO₄ is equivalent to

a) 100 ml of 0.05 M H₂C₂O₄

b) 50 ml of 0.05 M H₂C₂O₄

c) 25 ml of 0.2 M H₂C₂O₄

d) 50 ml of 0.10 M H₂C₂O₄

Answer: 50 ml of 0.05 M H₂C₂O₄

Question: Which of the following is soluble in yellow ammonium sulphide?

a) CuS

b) CdS

c) SnS

d) PbS

Answer: SnS

Question: Which of the following cannot give iodometric titration?

a) Fe³⁺

b) Cu²⁺

c) Pb²⁺

d) Ag²⁺

Answer: Fe³⁺

Question: Acetaldehyde and acetone can be distinguished by :

a) Iodoform test

b) Nitroprusside test

c) Fehlings solution test

d) C & P test

Answer: Fehlings solution test

Question: When H₂S gas is passed through the HCl containing aqueous solution of CuCl₂, HgCl₂, BiCl₃ and CoCl₂ it does not precipitate out

a) CuS

b) HgS

c) Bi₂S₃

d) CoS

Answer: CoS

Question: Which one of the following statements is correct ?

a) From a mixed precipitate of AgCl and AgI, ammonia solution dissolves only AgCl

b) Ferric ions give a deep green precipitate on adding potassium ferrocyanide solution

c) On boiling a solution having K⁺, Ca²⁺ and  ions we get a precipitate of K₂Ca(CO₃)₂  

d) Manganese salts give a violet borax bead test in the reducing flame

Answer: From a mixed precipitate of AgCl and AgI, ammonia solution dissolves only AgCl

Question: Three separate samples of a solution of a single salt gave these results. One formed a white precipitate with excess ammonia solution, one formed a white precipitate with dil. HCl solution and one formed a black precipitate with H₂S. The salt could be

a) AgNO₃

b) Pb(NO₃)₂

c) Hg(NO₃)₂

d) MnSO₄

Answer: Pb(NO₃)₂

Question: Experiment to study kinetics of the dissociation of hydrogen peroxide must be performed by group of two or three so that–

a) when one is recording data other should be swirling flask at constant rate

b) Experiment can be performed by one student only as outcomes are independent on rate of mixing of mixture 1 and 3

c) For safety purpose

d) None of these

Answer: when one is recording data other should be swirling flask at constant rate

Question:  Ammonia forms the complex ion [Cu(NH₃)₄]²⁺ with copper ions in alkaline solutions but not in acidic solutions. What is the reason for it ?

a) In acidic solutions protons coordinate with ammonia molecules forming  NH₄⁺ ions and NH₃ molecules are not available

b) In alkaline solutions insoluble Cu(OH)₂ is precipitated which is soluble in excess of any alkali

c) Copper hydroxide is an amphoteric substance

d) In acidic solutions hydration protects copper ions

Answer: In acidic solutions protons coordinate with ammonia molecules forming  NH₄⁺ ions and NH₃ molecules are not available

Question: An aqueous solution of a substance gives a white precipitate on treatment with dil. HCl which dissolves on heating. When H₂S is passed through the hot acidic solution, a black precipitate is obtained. The substance is a

a)

b) Cu²⁺ salt

c) Ag⁺ salt

d) Pb²⁺ salt

Answer: Pb²⁺ salt

Question: The weight of oxalic acid required to neutralise 100 ml of normal NaOH

a) 6.3 g

b) 126 g

c) 530 g

d) 63 g

Answer: 6.3 g

Question: How do we differentiate between Fe³⁺ and Cr³⁺ in group III?

a) By taking excess of NH₄OH solution

b) by increasing NH₄⁺ ion concentration

c) by decreasing OH ^– ion concentration

d) Both (b) and (c).

Answer: Both (b) and (c).

Question: Which of the following pair is not distinguished by passing H₂S ?

a) Hg, Pb

b) Cd, Pb

c) As, Cd

d) Zn, Mn

Answer: Hg, Pb

Question: A little dilute hydrochloric acid is dropped on a pH paper. The colour of the pH paper turns to

a) Dark pink

b) Light green

c) Light blue

d) Bright yellow

Answer: Dark pink

Question: A gas 'X' is passed through water to form a saturated solution. The aqueous solution on treatment with silver nitrate gives a white precipitate. The saturated aqueous solution also dissolves magnesium ribbon with evolution of a colourless gas 'Y'. Identify 'X' and 'Y'.

a) X = CO₂, Y = Cl₂

b) X = Cl₂, Y = CO₂

c) X = Cl₂, Y = H₂

d) X = H₂, Y = Cl₂

Answer: X = Cl₂, Y = H₂

Question: A one litre flask is full of brown bromine vapours. The intensity of brown colour of vapour will not decrease appreciably on adding to the flask some

a) Pieces of marble

b) Animal charcoal powder

c) Carbon tetrachloride

d) Carbon disulphide

Answer: Pieces of marble

Question: An organic compound is treated with NaNO₂ and dil. HCl at 0°C. The resulting solution is added to an alkaline solution of β-naphthol where by a brilliant red dye is produced. It shows the presence of

a) – NO₂ group

b) aromatic –NH₂ group

c) – CONH₂ group

d) Aliphatic – NH₂ group

Answer: aromatic –NH₂ group

Question: The gas that turns lime water milky is

a) CO₂

b) SO₂

c) Both of these

d) None of these

Answer: Both of these

Question: Phenol can be distinguished from ethyl alcohol by all reagents except

a) NaOH

b) FeCl₃

c) Br₂/H₂O

d) Na

Answer: Na

Question: The correct method of finding the pH of a solution is to

a) Heat the solution in a test tube and expose the pH paper to the vapours formed

b) Pour few drops of the solution from the test tube on the pH paper

c) Drop the pH paper in the solution

d) Put a drop of the solution on the pH paper using a dropper

Answer: Put a drop of the solution on the pH paper using a dropper

Question: Which of the following impart green colour to the burner flame?

a) B(OMe)₃

b) Na(OMe)

c) Al(OR)₃

d) Sn(OH)₂

Answer: B(OMe)₃

Question: A red solid is insoluble in water. However it becomes soluble if some KI is added to water. Heating the red solid in a test tube results in liberation of some violet coloured fumes and droplets of a metal appear on the cooler parts of the test tube. The red solid is

a) HgI₂

b) HgO

c) Pb₃O₄

d) (NH₄)₂Cr₂O₇

Answer: HgI₂

Question: A little dilute hydrochloric acid is dropped on a pH paper. The colour of the pH paper turns to

a) Dark pink

b) Light green

c) Light blue

d) Bright yellow

Answer: Dark pink

Question: Write the probable colour of the following salts.
(a) Ferrous salts
(b) Ammonium salts
(c) Cupric salts
(d) Calcium salts
(e) Aluminium Salts
Solution :
(a) Ferrous salts : Light green
(b) Ammonium salts : Colourless
(c) Cupric salts : Blue
(d) Calcium salts : Colourless
(e) Aluminium salts : Colourless

Question: Name:
(a) a metallic hydroxide soluble in excess of NH₄OH.
(b) a metallic oxide solube in excess of caustic soda solution.
(c) a strong alkali
(d) a weak alkali
(e) two coloured metal ions
(f) two coloured metal ions
(g) a metal that evolves a gas which burns with a pop sound when boiled with alkali solutions.
(h) two bases which are not alkalis but dissolves in alkalis to yield colourless solutions.
(j) a coloured cation not a representative element.
Solution :
(a) Cu(OH)₂
(b) ZnO
(c) NaOH
(d) NH₄OH
(e) Na⁺, Ca²⁺
(f) Fe²⁺, Mn²⁺
(g) Aluminium
(h) Zn(OH)₂ and Al(OH)₃
(i) PbO
(j) Ammonium ion

Question: Write balanced equations for Q.2 (g) and (i)
Solution : 2Al + 2NaOH + 2H₂O ⟶ 2NaAlO₂ + 3H₂
(Hot and conc.)             Sodium meta aluminate
                                       (colourless)
PbO + 2NaOH ⟶ Na₂PbO₂ + H₂O
(Yellow)               sodium plumbate
                           (colourless, soluble)

Question: What happens when ammonia solution is added first dropwise and then in excess to the following solution:
(i) CuSO₄ (ii) ZnSO₄ (iii) FeCI₃
Write balanced equations for these reactions.
Solution :
(i) CuSO₄ + 2NH4OH ⟶ Cu(OH)₂ ↓ (NH₄)₂ SO₄
Blue pale blue ppt. colourless is solution
With excess of NH₄OH, ppt dissolves
CU(OH)₂ + (NH₄)₂SO₄ + 2NH₄OH ⟶ [Cu(NH₃)₄]SO₄ + 4H₂O
                                   Excess           Tetrammine
                                                         Copper(II) Sulphate
(ii) ZnSO₄ + 2NH₄OH ⟶ Zn(OH)₂ + (NH₄)₂ SO₄
Colourless white, gelatinous ppt colourless With excess of NH₄OH, ppt dissolves
Zn(OH)₂ + (NH₄)₂SO₄ + 2NH₄OH ⟶ [Zn(NH₃)4]SO₄ + 4H₂O
                                           (excess)    Tetramminezinc(II) Sulphate
                                                             (colourless)
(iii) FeCI₃ + 3NH₄OH ⟶ Fe(OH)₃ ↓ + 3NH₄CI
Yellow solution reddish brown ppt. colourless in solution

Question: What do you observe when caustic soda solution is added to the following solution, first a little and then in excess:
(a) FeCI₃
(b) ZnSO₄
(c) Pb(NO₃)₂
(d) CuSO₄
Write balanced equations for these reactions.
Solution :
(i) FeCI₃ + 3NaOH ⟶ Fe(OH)₃ ↓ 3 NaCI
Yellow                    reddish brown, ppt   colourless in solution
In excess of alkali, the reddish brown ppt, of Fe(OH)₃ remains insoluble

(ii) ZnSO₄ + 2NaOH ⟶ Zn(OH)₂ ↓ + NaSO₄
Colourless white gelatinous ppt. colourless
In excess of alkali, white gelatinous ppt. of Zn(OH)₂ becomes soluble
Zn(OH)₂ + 2NaOH (Excess) ⟶ Na2ZnO₂ + 2H₂O
                                          Sodium zincate (colourless)

(iii) Pb(NO₃)₂ + 2NaOH ⟶ Pb(OH)₂ ↓ + 2NaNO₃
                                        White ppt (colourless)
In excess of alkali, white precipitate of Pb(OH)₂ becom essoluble:
Pb(OH)₂ + 2NaOH(excess) ⟶ Na₂PbO₂ + 2H₂O
                                         Sodium plumbate
                                         {colourless}
CuSO₄ + 2NaOH ⟶ Cu(OH)₂ ↓ + 2NaSO₄
Blue colourless pale blue ppt. { colourless}
In excess of alkali, pale blue precipitate of Cu(OH)₂ is insoluble

Question: Name the chloride of a metal which is soluble in excess of ammonium hydroxide. Write equation for the same.
Solution : Zinc chloride (ZnCl₂) is soluble in excess of ammonium hydroxide.
ZnCI₂ + 2NH₄OH ⟶ Zn(OH)₂ ↓ 2NH₄CI
Colourless White gelatinous ppt.
With excess of NH₄oh ppt dissolves
Zn(OH)₂ + 2NH₄CI + 2NH₄OH (excess) ⟶ [Zn(NH₃)₄]CI₂ + 4H₂O
                                                              Tetram mine zinc (II) Chloride
                                                               Colourless

Question: On adding dilute ammonia solution to a colourless solution of a salt, a white gelatinous precipitate appears. This precipitate however dissolves on addition of excess of ammonia solution identify (choose from Na, Al, Zn, Pb, Fe)
(a) Which metal salt solution was used?
(b) what is the formula of the white gelatinous precipitate obtained?
Solution :
(a) ZnCl₂
(b) Zn(OH)₂

Question: Name:
(a) a yellow monoxide that dissolves in hot and concentrated caustic alkali
(b) a white, insoluble oxide that dissolves when fused with caustic soda or caustic potash
(c) a compound containing zinc in the anion
Solution :
(a) PbO
(b) ZnO
(c) K2ZnO₂

Question: What do you observe when freshly precipitated aluminium hydroxide reacts with caustic soda solution? Give balanced equation.
Solution :
(a) (iii)
Aqueous solution of copper sulphate is blue.
(b) (iii)
FeSO₄ + 2NaOH → Fe(OH)₂ + Na2SO₄
(Dirty green, (Colourless)
gelatinous ppt.)
(c) (iii)
Zn + 2NaOH → Na2ZnO₂ + H₂
Sodium zincate
(Colourless)
Zz Zn + HCl → ZnCl₂ + H₂

Question: What do you understand by amphoteric oxide Give the balanced equations for the reaction with three different amphoteric oxides with a caustic alkali. Write you observation if any.
Solution : When freshly precipitated aluminum hydroxide reacts with caustic soda solution, whitesalt of sodium meta aluminate is obtained.
Al(OH)₃ + NaOH → NaAlO₂ + 2H₂O
Sodium meta aluminate

Question: Distinguish by adding:
(a) sodium hydroxide solution and
(b) Ammonium hydroxide solution to
(i) Calcium salt solution and lead salt solution
(ii) Lead salt solution and ferrous salt solution
(iii) copper salt solution and ferrous salt solution
(iv) Fe (II) salt solution and Fe (III) Salt solution
(v) Ferrous nitrate and lead nitrate
Solution : (a) Distinguish by adding Sodium hydroxide solution:

(i) Ca(NO₃)₂ + 2NaOHCa(OH)₂ + 2NaNO₃
On adding excess of NaOH, ppt. of Ca (OH)₂ is sparingly soluble.
Pb(NO₃)₂ + 2NaOHPb(OH)₂ + 2NaNO₃
On adding excess of NaOH, ppt of Pb(OH)₂ is soluble.

(ii) Pb(NO₃)₂ + 2NaOHPb(OH)₂ + 2NaNO₃
On adding excess of NaOH, ppt of Pb(OH)₂ is soluble.
ZnSO₄ + 2NaOHZn(OH)₂ + Na₂SO₄
With excess of NaOH, white gelatinous ppt. of Zn (OH)₂ is soluble. So, these two cannot be distinguished by NaOH alone. However white ppt. of Pb (OH)₂ is readily soluble in acetic acid also.

(iii) CuSO₄ + 2NaOHCu(OH)₂ + Na₂SO₄
With excess of NaOH, alkali pale blue ppt of Cu (OH)₂ is insoluble.
FeSO₄ + 2NaOHFe(OH)₂ + Na₂SO₄
With excess of NaOH, dirty green ppt. of Fe(OH)₂ is insoluble.

(iv) FeSO₄ + 2NaOHFe(OH)₂ + NaSO₄
With excess of NaOH, dirty green ppt of Fe (OH)₂ is insoluble.
FeCl₃ + 3NaOHFe(OH)₃ + 3NaCl
With excess of NaOH, reddish brown ppt of Fe (OH)₃ is insoluble.

(b) Distinguish by adding Ammonium hydroxide solution:

(i) On addition of NH₄OH to calcium salts no precipitation of Ca (OH)₂ occurs even with addition of excess of NH₄OH because the concentration of OH-ions from ionization of NH₄OH is so low that it cannot precipitate the hydroxide of calcium.
Pb(NO₃)₂ + 2 NH₄OHPb(OH)₂ + 2NH₄NO₃
On adding excess of NH4OH, chalky white ppt. of Pb (OH)₂ is insoluble.

(ii) Pb(NO₃)₂ + 2 NH₄OHPb(OH)₂ + 2NH₄NO₃
On adding excess of NH₄OH, chalky white ppt. of Pb(OH)₂ is insoluble.
ZnSO₄ + 2NH₄OHZn(OH)₂ + (NH₄)₂SO₄
With excess of NH₄OH, white gelatinous ppt. of Zn (OH)₂ is soluble.

(iii) CuSO₄ + 2NH₄OHCu(OH)₂ + (NH4)₂SO₄
With excess of NH₄OH, pale blue ppt. of Cu (OH)₂ is soluble.
FeSO₄ + 2NH₄OHFe(OH)₂ + (NH₄)₂SO₄
With excess of NH₄OH, dirty green ppt. of Fe (OH)₂ is insoluble.

(iv) FeSO₄ + 2NH₄OHFe(OH)₂ + (NH₄)₂SO₄
With excess of NH₄OH, dirty green ppt. of Fe (OH)₂ is insoluble.
FeCl₃ + 3NH₄OHFe(OH)₃ + 3NH₄Cl
With excess of NH₄OH, reddish brown ppt of Fe (OH)₃ is insoluble.

Question: You are provided with two reagent bottles marked A and B. One of which contains NH₄OH solution and the other contains NaOH solution. How will you identify them by a chemical test?
Solution : Reagent bottles A and B can identified by using calcium salts such as Ca(NO₃)₂.
On adding NaOH to Ca (NO₃)₂, Ca (OH) ₂ is precipitated as white precipitate which is sparingly soluble in excess of NaOH.
Ca(NO₃)₂ + 2NaOH⟶ Ca(OH)₂ + 2NaNO₃
Whereas, on addition of NH₄OH to calcium salts, no precipitation of Ca(OH)₂ occurs even with addition of excess of NH₄OH because the concentration of OH-ions from the ionization of NH₄OH is so low that it cannot precipitate the hydroxide of calcium.
So the reagent bottle which gives white precipitate is NaOH and the other is NH₄OH.

Question: What do you understand by the following:
(i) Analysis
(ii) Qualitative analysis
(iii) Reagent
(iv) Precipitation
Solution :
(i) Analysis: The determination of chemical components in a given sample is called analysis.
(ii) Qualitative analysis: The analysis which involves the identification of the unknown substances in a given sample is called qualitative analysis.
(iii) Reagent: A reagent is a substance that reacts with another substance.
(iv) Precipitation: It is the process of formation of an insoluble solid when solutions are mixed. The solid thus formed is called precipitate.

Question: Write the probable colour of the following salts:
(i) Iron (III) chloride
(ii) Potassium nitrate
(iii) Ferrous sulphate
(iv) Aluminium acetate
(v) Calcium carbonate
Solution :
(i) Yellow
(ii) Colourless
(iii) PaleGreen
(iv) Colourless
(v) Colourless

Question: Name the probable cation present in each of the following solution:
(i) Yellow coloured solution
(ii) blue coloured solution
(iii) Light blue coloured solution
(iv) Pink coloured solution
Solution :
(i) Fe³⁺
(ii) Cu²⁺
(iii) Cu⁺²
(iv) Mn²⁺

Question: Name the metal hydroxides which are:
(i) Sparingly soluble
(ii) Insoluble
(iii) Soluble
In caustic soda solution
Solution :
(i) Ca(OH)₂
(ii) Fe(OH)₂ and Cu(OH)₂
(iii) Zn(OH)₂ and Pb(OH)₂

Question: What do you observe when ammonium salt is heated with caustic soda solution? Write the balanced equation.
Solution : When ammonium salt is heated with caustic soda solution, ammonia gas is evolved.
The balance equation is:
NH₄Cl + NaOH Δ NaCl + H₂O + NH₃
                      →
(NH₄)2SO₄ + 2NaOH  Δ  Na2SO₄ + 2H₂O + 2NH₃
                                →

Question: How will you distinguish NH4OH solution from NaOH solution?
Solution : NH₄OH and NaOH can be distinguished by using calcium salts.
For example on adding NaOH to Ca(NO₃)₂, Ca(OH)₂ is obtained as white precipitate which is sparingly soluble in excess of NaOH.
Ca(NO₃)₂ + 2NaOH Ca(OH)₂ + 2NaNO₃
On addition of NH₄OH to calcium salts, no precipitation of Ca(OH)₂ occurs even with the addition of excess of NH₄OH. This is because the concentration of OH- ions from the ionization of NH₄OH is so low that it cannot precipitate the hydroxide of calcium.

Question: Name the metal hydroxides which are:
(i) Insoluble (ii) Soluble.
In ammonium hydroxide solution
Solution :
(i) Fe(OH)₂ and Pb(OH)₂
(ii) Cu(OH)₂ and Zn(OH)₂