94420 + Interview Questions in Chemistry in Class 12

1.	On addition of an inert gas at constant volume to the reaction : N_2 + 3H_2 hArr 2NH_3 at equilibrium:
Answer» The REACTION halts forward reaction is favoured The reaction REMAINS unaffected Backward reaction is favoured Answer :C

Discussion

2.	On addition of ammonium chloride to a solution of ammonium hydroxide
Answer» Dissociation of `NH_(4)OH` increases Concentrationof `OH^(-)` increases Concentration of `OH^(-)` decreases Concentration of `NH_(4)^(+)` and `oH^(-)` increases Solution :DUE to common ION effect.

Discussion

3.	On addition of AgNO_3 to NaCl, white ppt. occurs
Answer» INSTANTANEOUSLY with a measurable SPEED SLOWLY very SLOW Solution :Ionic REACTION are instantaneous one.

Discussion

4.	On addition of ammonium chloride to a solution of ammonium hydroxide ……….
Answer» DISSOCIATION of `NH_4OH` increases concentration of OH increases concentration of `OH^-` decreases concentration of `NH_4^+ and OH^-` increases Solution :Due to common ion EFFECT

Discussion

5.	On addition of AgNO_3 to NaCl, white ppt, occurs:
Answer» Instantaneously With a MEASURABLE speed Slowly None Answer :A

Discussion

6.	On addition of 1 ml of solution of 10% NaCl to 100ml corporate gold sol in presence of 0.25g of starch, the coagulation is just prevented. The gold number of starch is
Answer» `0.025` `0.25` 2.5 25 Answer :D

Discussion

7.	On addition of 1 ml solution of 10% NaCl to 10 mL gold sol in the presence of 0.025 g of starch, the coagulation is just prevented. Starch has the gold number
Answer» 0.025 0.25 0.5 25 Solution :By definition, GOLD NUMBER of starch is the amount of starch in mg added to 10 mL STANDARD gold sol which PREVENTS the COAGULATION of gold on adding 1 mL of 10% NaCl solution. The amount of starch is 0.025 g = 25 mg. Hence, gold number is 25.

Discussion

8.	On addition of 2mL of 5% NaCl to 10 mL gold sol in the presence of 0.025 g starch , the coagulation is just prevented. What is the gold number of starch ?
Answer» Solution : 0.025 g of STARCH just prevent the coagulation of 10mL GOLD sol on the addition of 2mL of 5% NaCl or 0.025 g of starch just prevents the coagulation of 10mL gold sol on the addition of 1ML of 10% NaCl. Milligrams of starch which just prevent the coagulation of 10mL gold sol. on the addition of 1 mL 10% NaCl = 25 `:.` Gold number of starch = 25 .

Discussion

9.	On additing (A) into a dilute solution of silver nitrate a white precipitate appears which quickly changes into a black coloured compound. (C)
Answer» Answer :The REACTIONS indicate that the COMPOUND (A) is sodium THIOSULPHATE. It is formed in step (i) by passing gas (B) which is either `I_(2)`. `2AgNO_(3)+ underset("(Whitw ppt)")(Na_(2)S_(2)O_(3) rarr) Ag_(2)S_(2)O_(3)+2NaNO_(3)` `Ag_(2)S_(2)O_(3)+underset((C)" black")(H_(2)Orarr) Ag_(2)S+H_(2)SO_(4)`

Discussion

10.	On adding two or three drops of FeCl_(3) into the excess of solution (A) a violet coloured compound (D) is formed. This colour disapperars quickly.
Answer» ANSWER :The reactions indicate that the compound (A) is sodium thiosulphate. It is formed in step (i) by passing gas (B) which is either `I_(2)`. `S_(2)O_(3)^(2-)+Fe^(3+) underset((D)" violet")(RARR) [Fe^(3+)(S_(2)O_(3))_(2)]^(-)` `[Fe(S_(2)O_(3))_(2)]^(-)+Fe^(3+) rarr 2 Fe^(2+)+S_(4)O_(6)^(2-)`

Discussion

11.	On adding which of the following the pH of 20 mL of 0.1 N HCl will not alter ?
Answer» 1 mL of 1 N HCl 20 mL of DISTILLED WATER 1 mL of 0.1 N NaOH 500 mL of HCl of pH = 1. Solution :pH of 20 mL of `0.1 N HCl= -log [H^(+)]` `=-log (0.1)=1` The given solution has pH = 1 `therefore` When 500 mL of HCl of pH = 1 is added to the given solution, pH REMAINS same.

Discussion

12.	On adding which of the following the pH of 20 ml of 0.1 NaOH will not alter
Answer» 1 mL of 1N HCl 20 mL of DISTILLED water 1 mL of 0.1 N NaOH 500 mL of HCl of PH = 1 Answer :D

Discussion

13.	On adding solid pottasium cyanide to water :
Answer» PH will increase pH will decrease pH will not change Electrical CONDUCTANCE will not change Answer :A

Discussion

14.	On adding sold potassium cyanide to water
Answer» PH will increase pH will decrease pH will not change Electrical conducting will not change SOLUTION :`CN^(-) + H_(2)O rarr HCN + OH^(-)` Because `OH^(-)` concentration is increased.

Discussion

15.	On adding NaOH to ammonium sulphate, a colourless gas with pungent odour is evolved which forms a blue coloured complex with Cu^(2+) ion. Identify the gas.
Answer» Solution :Ammonium sulphate reacts with NaOH to evolve `NH_(3)` gas which has pungent smell and forms blue coloured complex with `Cu^(2+)` ions as shown below : `{:(UNDERSET("Amm. sulphate")((NH_(4))_(2)SO_(4)) + 2 NaOH RARR underset("Ammonia")(2NH_(3))uarr + Na_(2)SO_(4) + 2H_(2)O),(underset("Copper (II) ion")(Cu^(2+)(AQ.))+4NH_(3)(aq.) rarr underset(("Blue coloured complex"))underset("Tetraamminecopper (II) ion")([Cu(NH_(3))_(4)]^(2+)(aq.))):}`

Discussion

16.	On adding NaOH solution to the aqueous solution of K_(2)Cr_(2)O_(7), the colour of the solution changes from :
Answer» orange to yellow yellow to orange orange to red yellow to PINK. SOLUTION :Colour CHANGE fromorange to yellow.

Discussion

17.	On adding Na_(2)S to sodium nitro prusside solution
Answer» `Na_(4)[FE(CN)_(5)NOS]` complex is FORMED `[Fe(CN)_(5)NOS]^(-4)` complex is formed a violet colour is formed All of the above Solution :`Na_(2)S+Na_(2)[Fe(CN)_(3)NO] to Na_(4)underset("Violet")([Fe(CN)_(5)NOS])`

Discussion

18.	On adding of conc. H_(2)SO_(4)ot a chloride salt colourless fumes are evolved but in case of iodide salt. Violet fumes come out. This is because
Answer» HIis of violet colour HI gets oxidised to `I_(2)` HI changes to `HIO_(3)` `H_(2)SO_(4)` reducesHI to `I_(2)` Solution :HI gets oxidised to `I_(2).2I^(-)+H_(2)SO_(4) to SO_(4)^(2o+)+2HI,` `H_(2)SO_(4) to H_(2)O+SO_(2)+(O), 2HI+O to H_(2)O +I_(2)`

Discussion

19.	On adding Kl solution to a solution of CuSO_4, a white precipitate of ….. Is formed .
Answer» POTASSIUM SULPHATE Cuprous sulphate Cuprous IODIDE CUPRIC iodide Answer :C

Discussion

20.	On adding FeCl_(3) to the acidic Lassaigne solution, a blood red colouration is obtained. It indicates the presence of :
Answer» S N N and S N and halogen Answer :C

Discussion

21.	On adding excess of ammonium hydroxide to a copper chloride solution
Answer» A DEEP blue solution is obtained No change is observed Blue PRECIPITATE of COPPER hydroxide is obtained Black precipitate of copper oxide is obtained Solution :On addingexcess of ammonium hydroxide to a copperchloride solution a deep blue solution of `[Cu(NH_(3))_(4)]^(2+)` ion is FORMED.

Discussion

22.	On adding excess of ammonium hydroxide to a copper chloride solution :
Answer» BLUE precipitate of COPPER hydroxide hydroxide is obtained BLACK precipitate of copper oxide is obtained A DEEP blue solution is obtained No change is observed Answer :C

Discussion

23.	On adding conc. H_2SO_4to a salt, brown colouration was observed on the walls of the test tube, On heating, violet coloured vapours were evolved. The brown colouration is due to the formation of
Answer» `l_(2)`(s) L `l_(3)^(-)` Hl Answer :C

Discussion

24.	On adding ammonium hydoxide solution to Al_(2)(SO_(4))_(3) (aq):
Answer» A PERCIPITATE is formed which does not DISSOLVE in EXCESS of ammonium hydoxide A percipitate is formed which DISSOLVES in excess of ammonia solution No precipitate is formed None of these Solution :`Al_(2)(SO_(4))_(3)+6NH_(4)OH to 2Al(OH)_(3)+3(NH_(4))_(2)SO_(4)` `Al(OH)_(3)+NaOH to Na^(+)[Al(OH)_(4)]^(-)` sulublecomplex it is insoluble in `NH_(4)OH`

Discussion

25.	On adding ammonium hydroxide solution to aqueous solution of Al_2(SO_4)_3 :
Answer» A precipitate is FORMED which DISSOLVES in EXCESS of ammonia solution A precipitate is formed which does not dissolve in excess of ammonium hydroxide No precipitate is formed None of these Answer :B

Discussion

26.	On adding AgNO_(3) solution to a solution of [Pt(NH_(3))_(3)Cl_(3)]Cl. The percentage of total chloride ion precipitated is–
Answer» 100 75 50 25 Solution :% of CHLORINE`=("ionised CL")/("TOTAL Cl") XX 100`

Discussion

27.	On adding AgNO_(3) solution to KI solution, a negatively charged colloidal sol will be formed in which of the following conditions?
Answer» 100 mL of 0.1M `AgNO_(3) + 100 mL`of 0.1 M kl 100 MLOF 0.1 M `AgNO_(3)` + 50 mL of 0.2 m KI 100 mL of 0.2 M `AgNO_(3)` + 100 mL of 0.1 M KI 100 mL of 0.1 M `AgNO_(3)` + 100 mL of 0.15 M KI Answer :D

Discussion

28.	On adding ammonium chloride to a solution ammonium hydroxide
Answer» DISSOCIATION of `NH_4OH` increases Concentration of OH increases Concentration of OH decreases Concentration of OH REMAINS unchanged Answer :C

Discussion

29.	On adding a solution of (A) into the solution of cupric chloride, a white precipitate is first formed which dis- solves on adding excess of (A) forming a compound (E). Identify (A) to (E) and give chemical equations for the reactions at steps (i) to (iv).
Answer» Answer :The REACTIONS indicate that the compound (A) is sodium thiosulphate. It is FORMED in step (i) by passing gas (B) which is either `I_(2)`. `2Cu^(2+)+underset("white ppt.")(3S_(2)O_(3)^(2-) rarr) Cu_(2)S_(2)O_(3) darr +S_(4)O_(6)^(2-)` `underset("White ppt.")(3Cu_(2)S_(2)O_(3)) darr +underset("(excess)")(2Na_(2)S_(2)O_(3)) rarr underset("(E) soluble complex")(Na_(4)[Cu_(6)(S_(2)O_(3))_(5)])`

Discussion

30.	On adding AgNO_(3) solution to KI solution, a negatively charged colloidal sol will be formed in which of the following conditions ?
Answer» `100ML " of " 0.1M AgNO_3 + 100ml " of " 0.1M KI ` `100ml " of " 0.1M AgNO_3 + 100ml " of " 0.2M KI ` `100ml " of " 0.2M AgNO_3 + 100ml " of " 0.1M KI ` `100ml " of " 0.15M AgNO_3 + 100ml " of " 0.15M KI ` SOLUTION :`AgNO_3 +underset(("EXCESS"))(KIto) -ve` SOL

Discussion

31.	On adding a solute, vapourpressure increases .(true/false)
Answer» SOLUTION :DECREASES

Discussion

32.	On adding a solute, vapour pressure _____ .
Answer» SOLUTION :DECREASES .

Discussion

33.	On adding a solute, osmotic pressure _____ .
Answer» SOLUTION :INCREASES .

Discussion

34.	On increasing concentration of a solution, osmotic pressure _____ .
Answer» SOLUTION :INCREASES .

Discussion

35.	On adding a solute, freezing point of solution _____ .
Answer» SOLUTION :DECREASES

Discussion

36.	On adding a solute,boiling point of solution _____ .
Answer» SOLUTION :ELEVATES (i.e.increase)

Discussion

37.	On adding a few drops of dil HCl to a freshly precipitated ferric hydroxide, a red coloured colloidal sol 9 obtained. This phenomenon is called:
Answer» PEPTISATION Dialysis Protective Dissolution. Answer :A

Discussion

38.	On adding 0.1 M solution each of [Ag^(+)], [Ba^(2+)], [Ca^(2+)] in a Na_(2)SO_(4) solution, species first precipitated is [K_(sp) BaSO_(4) = 10^(-11), K_(sp)CaSO_(4) = 10^(-6), K_(sp)Ag_(2)SO_(4) = 10^(-5)] Least solubility is of BaSO_(4), hence it will precipitate first.
Answer» `Ag_(2)SO_(4)` `BaSO_(4)` `CaSO_(4)` All of these Solution :SOLUBILITY of `BaSO_(4)(x) = sqrt(K_(sp)) = sqrt(10^(-11))` `= 3.16 xx 10^(-6)` mol/L. Solubility of `CaSO_(4)(x) = sqrt(K_(sp)) = sqrt(10^(-6))` `= 1.0 xx 10^(-3)` mol/L. Solubility of `Ag_(2)SO_(4) = 3sqrt((K_(sp))/(4))` (`because` for `Ag_(2)SO_(4), 4x^(3) = K_(sp)`) `= 3sqrt((10^(-5))/(4)) = 1 xx 10^(-2)` mol/L

Discussion

39.	On adding 20 ml of 0.1 N NaOH solution to 10 ml of 0.1 HCl, the resulting solution will
Answer» have no EFFECT on red or blue LITMUS paper turn blue litmus red turn methgyl orange red turn PHENOPHTHALEIN SOLUTION pink Answer :D

Discussion

40.	On addiction of 1ml solution of 10% NaCl to 10ml gold sol in the presence of 0.0250gm mof starch, the coagulation is just prevented Starch has the following gold number
Answer» 0.025 0.25 2.5 25 Answer :D

Discussion

41.	On acid hydrolysis, propane nitrile gives
Answer» propanal acetic ACID PROPIONAMIDE PROPANOIC acid ANSWER :D

Discussion

42.	On a week end, Shubham went on a picnic with this his parents. There was a beautiful view of a lake but suddenly, Shubham saw some fish floating on the surface of water of the lake as they had died. Shubham asked his parents why these fish had died. They told him that fish also need oxygen for their survival as we do. Dissolved oxygen in the water gets depleted due to discharge of human sewage and organic wastes of the industries into the lake water. After reading the above paragraph, answer the following questions: (a) What lesson do you learn from the explanation given by Shubham's parents to him?
Answer» Solution :(a) We should not THROW HUMAN sewage and ORGANIC wastes of the INDUSTRIES into lakes.

Discussion

43.	On absorbing light of wavelength 3800 A, bromine molecule undergoes dissociation and form atoms. The kinetic energy of one bromine atom assuming that one quantum of radiation is absorbed by each molecule would be (Bond energy of Br_2=190kJ/mol)
Answer» `1.04`x `10^(-19) J` `2.08`x`10^(-19) J` `1.25` x `10^(-5) J` `6.25` x`10^(-1) J` ANSWER :A

Discussion

44.	On a week end, Shubham went on a picnic with this his parents. There was a beautiful view of a lake but suddenly, Shubham saw some fish floating on the surface of water of the lake as they had died. Shubham asked his parents why these fish had died. They told him that fish also need oxygen for their survival as we do. Dissolved oxygen in the water gets depleted due to discharge of human sewage and organic wastes of the industries into the lake water. After reading the above paragraph, answer the following questions: (b) Hoe dissolved oxygen gets depleted due to presence of the organic waste?
Answer» SOLUTION :(b) MICROORGANISMS which decompose the organic WASTE need oxygen. The AMOUNT of oxygen consumed is proportional t the amount of waste present. THUS, sufficient dissolved oxygen no longer remains available for the survival of the fish .

Discussion

45.	On a give condition, the equilibrium concentration of HI, H_(2) and I_(2) are 0.80,1.10 mole/litre. The equlibrium constant for the reaction H_(2)+I_(2)hArr 2HI will be
Answer» 64 12 8 `0.8` SOLUTION :`H_(2)+I_(2)hArr2HI,[HI]=0.08,[H_(2)]=0.10,[I_(2)]=0.10` `K_(c)=([HI]^(2))/([H_(2)][I_(2)])=(0.08xx0.80)/(0.10xx0.10)=64`

Discussion

46.	On a certain hill station, pure water is found to boil at 95^(@)C. How many grams of NaCl must be added to 2 kg of water so that it boils at 100^(@)C?
Answer» SOLUTION :`DeltaT_(b)=100-95=5^(@),DeltaT_(b)=iK_(b)m"or"m=(DeltaT_(b))/(iK_(b))=(5)/(2xx0.52)=4.807` `"1000 G should CONTAIN NaCl = 4.807 moles "=4.807xx58.5g` `therefore"2000 g should contain NaCl "=2xx4.807xx58.7=562.42g.`

Discussion

47.	On a certain day the vapour pressure is 14 mm of Hg for water vapour in air at 20^@C . The saturated vapour pressure is 17.5 mm. How many moles of water vapour per litre of air would be required to saturate air at this temperature ?
Answer» `9.41 XX 10^(-4) ` `9.14 xx 10^(-4)` `1.914 xx 10^(-4) ` `4.19 xx 10^(-4)` ANSWER :C

Discussion

48.	On 100% dissociation of the compound K_(4)Fe(CN)_(6), the total number of ions produced will be
Answer» SOLUTION :`K_(4)[FE(CN)_(6)] implies4K^(+)+[Fe(CN)_(6)]^(4-)`

Discussion

49.	ompound (X) of molecular formula C_5H_8Odoes not react appreciably with Lucasreagent at room temperature but gives a precipitate with amm. silver nitrate. With excess of MeMgBr, 0.42 g of (X) gives 224 mL of CH_4at STP. Treatment of (X) with H_2in the presence of Pt catalyst followed by boiling with excess HI, gives n-pentane. Suggest the structure for (X).
Answer» SOLUTION :`HC -= "CCH"_2 CH_2CH_2OH`

Discussion

50.	Omeprazole, rabeprazole, iso flurane, ranitidine, cemitidine.
Answer» Solution : Isoflurane. It is an ANAESTHETIC WHEREAS OTHERS are ANTACIDS.

Discussion

Explore topic-wise InterviewSolutions in Current Affairs.

On addition of an inert gas at constant volume to the reaction : N_2 + 3H_2 hArr 2NH_3 at equilibrium:

On addition of ammonium chloride to a solution of ammonium hydroxide

On addition of AgNO_3 to NaCl, white ppt. occurs

On addition of ammonium chloride to a solution of ammonium hydroxide ……….

On addition of AgNO_3 to NaCl, white ppt, occurs:

On addition of 1 ml of solution of 10% NaCl to 100ml corporate gold sol in presence of 0.25g of starch, the coagulation is just prevented. The gold number of starch is

On addition of 1 ml solution of 10% NaCl to 10 mL gold sol in the presence of 0.025 g of starch, the coagulation is just prevented. Starch has the gold number

On addition of 2mL of 5% NaCl to 10 mL gold sol in the presence of 0.025 g starch , the coagulation is just prevented. What is the gold number of starch ?

On additing (A) into a dilute solution of silver nitrate a white precipitate appears which quickly changes into a black coloured compound. (C)

On adding two or three drops of FeCl_(3) into the excess of solution (A) a violet coloured compound (D) is formed. This colour disapperars quickly.

On adding which of the following the pH of 20 mL of 0.1 N HCl will not alter ?

On adding which of the following the pH of 20 ml of 0.1 NaOH will not alter

On adding solid pottasium cyanide to water :

On adding sold potassium cyanide to water

On adding NaOH to ammonium sulphate, a colourless gas with pungent odour is evolved which forms a blue coloured complex with Cu^(2+) ion. Identify the gas.

On adding NaOH solution to the aqueous solution of K_(2)Cr_(2)O_(7), the colour of the solution changes from :

On adding Na_(2)S to sodium nitro prusside solution

On adding of conc. H_(2)SO_(4)ot a chloride salt colourless fumes are evolved but in case of iodide salt. Violet fumes come out. This is because

On adding Kl solution to a solution of CuSO_4, a white precipitate of ….. Is formed .

On adding FeCl_(3) to the acidic Lassaigne solution, a blood red colouration is obtained. It indicates the presence of :

On adding excess of ammonium hydroxide to a copper chloride solution

On adding excess of ammonium hydroxide to a copper chloride solution :

On adding conc. H_2SO_4to a salt, brown colouration was observed on the walls of the test tube, On heating, violet coloured vapours were evolved. The brown colouration is due to the formation of

On adding ammonium hydoxide solution to Al_(2)(SO_(4))_(3) (aq):

On adding ammonium hydroxide solution to aqueous solution of Al_2(SO_4)_3 :

On adding AgNO_(3) solution to a solution of [Pt(NH_(3))_(3)Cl_(3)]Cl. The percentage of total chloride ion precipitated is–

On adding AgNO_(3) solution to KI solution, a negatively charged colloidal sol will be formed in which of the following conditions?

On adding ammonium chloride to a solution ammonium hydroxide

On adding a solution of (A) into the solution of cupric chloride, a white precipitate is first formed which dis- solves on adding excess of (A) forming a compound (E). Identify (A) to (E) and give chemical equations for the reactions at steps (i) to (iv).

On adding AgNO_(3) solution to KI solution, a negatively charged colloidal sol will be formed in which of the following conditions ?

On adding a solute, vapourpressure increases .(true/false)

On adding a solute, vapour pressure _____ .

On adding a solute, osmotic pressure _____ .

On increasing concentration of a solution, osmotic pressure _____ .

On adding a solute, freezing point of solution _____ .

On adding a solute,boiling point of solution _____ .

On adding a few drops of dil HCl to a freshly precipitated ferric hydroxide, a red coloured colloidal sol 9 obtained. This phenomenon is called:

On adding 0.1 M solution each of [Ag^(+)], [Ba^(2+)], [Ca^(2+)] in a Na_(2)SO_(4) solution, species first precipitated is [K_(sp) BaSO_(4) = 10^(-11), K_(sp)CaSO_(4) = 10^(-6), K_(sp)Ag_(2)SO_(4) = 10^(-5)] Least solubility is of BaSO_(4), hence it will precipitate first.

On adding 20 ml of 0.1 N NaOH solution to 10 ml of 0.1 HCl, the resulting solution will

On addiction of 1ml solution of 10% NaCl to 10ml gold sol in the presence of 0.0250gm mof starch, the coagulation is just prevented Starch has the following gold number

On acid hydrolysis, propane nitrile gives

On absorbing light of wavelength 3800 A, bromine molecule undergoes dissociation and form atoms. The kinetic energy of one bromine atom assuming that one quantum of radiation is absorbed by each molecule would be (Bond energy of Br_2=190kJ/mol)

On a give condition, the equilibrium concentration of HI, H_(2) and I_(2) are 0.80,1.10 mole/litre. The equlibrium constant for the reaction H_(2)+I_(2)hArr 2HI will be

On a certain hill station, pure water is found to boil at 95^(@)C. How many grams of NaCl must be added to 2 kg of water so that it boils at 100^(@)C?

On a certain day the vapour pressure is 14 mm of Hg for water vapour in air at 20^@C . The saturated vapour pressure is 17.5 mm. How many moles of water vapour per litre of air would be required to saturate air at this temperature ?

On 100% dissociation of the compound K_(4)Fe(CN)_(6), the total number of ions produced will be

Omeprazole, rabeprazole, iso flurane, ranitidine, cemitidine.