94420 + Interview Questions in Chemistry in Class 12

1.	Correct decreasing order of acidity of oxides is
Answer» `Cl_(2)O_(7) GT SO_(3) gt P_(4)O_(10) gt SiO_(2)` `SO_(3) gt Cl_(2)O_(7) gt P_(4)O_(10) gt SiO_(2)` `SiO_(2) gt Cl_(2)O_(7) gt SO_(3) gt P_(4)O_(10)` `Cl_(2)O_(7) gt P_(4)O_(10) gt SO_(3) gt SiO_(2)` ANSWER :A

Discussion

2.	Correct combination for the preparation of Meoverset(18)OH will be :
Answer» III, ii, p III, `i`, q II, iv, s III, iii, p Answer :B

Discussion

3.	Correct coombination which gives at last two organic compounds having underset(.)O^(18) in it after propanation :
Answer» II. Iv, q IV, III, r II, iii, p all of these Answer :D

Discussion

4.	CORRECT combination among the following is
Answer» (II) (IV) (Q) (I) (III) (S) (III) (i)(P) (IV) (ii) (R) Answer :B

Discussion

5.	Correct atomic size is :-
Answer» `Li GT I gt F lt CL lt Br` `I gt Li gt F lt Cl gt Br` `I gt Br gt Cl gt F gt Li` `Li gt F lt I lt Br` ANSWER :A

Discussion

6.	Correct and rewrite the statement---- Ravi, Beas river dispute was resolved between Himachal Pradesh, Punjab and Uttarakhand.
Answer» SOLUTION :Ravi, BEAS river DISPUTE was RESOLVED between Punjab, Haryana and Rajasthan.

Discussion

7.	Correct among the following
Answer» Cs is BEST oxidising agent DUE to lowest I.E. `Li^(+)` is best REDUCING agent due to highest `\|Delta_(hyd)H^(Theta)\|` `Li^(+)` is best reducing agent due to highest `Delta_(hyd)H^(Theta)` `Cs^(+)` is best oxidising agent due to low `\|Delta_(hyd)H^(Theta)\|` ANSWER :B

Discussion

8.	Correct acidic strength of the following carboxylic acids A) C_(6) H_(5) COOH B) o-NO_(2) (C_(6) H_(4)) COOH C) p- NO_(2) (C_(6) H_(4)) COOH D) m- NO_(2) (C_(6) H_(4)) COOH
Answer» `A GT B gt C gt D` `B gt C gt D gt A ` `B gt D gt A gt C ` `B gt D gt C gt A` ANSWER :B

Discussion

9.	Carbon 14 is used to determine the age of organic material. The procerdure is based on the formationof .^(14)C by neutroncapture in the upper atmosphere. ._(7)^(14)N + ._(0)^(1)n rarr ._(6)^(14)C + ._(1)n^(1) .^(14)C is abosorbed by living organisms duringphostosythesis. The .^(14)Ccontent is constant in living organismsonce theplant or animal dies, the uptake of carbon dioxide by it ceases and the level of .^(14)C in the deadbeing, falls due to thedecay which.^(14)C undergoes. ._(6)^(14)C rarr ._(7)^(14)C+ beta^(-) The half-life period of .^(14)C is 5770 years. The decay constant (lambda) can be calculated by usingthe following formula lambda = (0.693)/(t_(1//2)) The comparison fo the beta^(-)activity fo the dead matterwiththat of the carbon still incirculation enables measurement of the period of the isolation the materail form the livingcycle. Themethod however, ceases to be accurate ever periodslonger than 30,000 years. The proportaion of .^(14)C to .^(12)C living matter is 1:10^(12). What should be the age of fossil for meainingful determination of its age?
Answer» 6 YEARS 6000 years 60000 years it can be used to CALCULATE any age Solution :As per the information given, the carbon dating method, ceases to be accurate over periods longer than `30,000 ` years. Hence the age of fossil for meaningful determination of its age should not be60000 years or 6 years (as it is quits LESSER than `t_(1//2)`) The age of fossil should be near the `t_(1//2) ` of `c^(14)`.i.e. 6000 years.

Discussion

10.	Carbon 14 is used to determine the age of organic material. The procedure is based on the formationof .^(14)C by neutroncapture in the upper atmosphere. ._(7)^(14)N + ._(0)^(1)n rarr ._(6)^(14)C + ._(1)p^(1) .^(14)C is absorbed by living organisms duringphotosynthesis. The .^(14)Ccontent is constant in living organismsonce theplant or animal dies, the uptake of carbon dioxide by it ceases and the level of .^(14)C in the deadbeing, falls due to thedecay which.^(14)C undergoes. ._(6)^(14)C rarr ._(7)^(14)N+ beta^(-) The half-life period of .^(14)C is 5730 years. The decay constant (lambda) can be calculated by usingthe following formula lambda = (0.693)/(t_(1//2)) The comparison of the beta^(-)activity of the dead matterwiththat of the carbon still incirculation enables measurement of the period of the isolation the material form the livingcycle. Themethod however, ceases to be accurate ever periodslonger than 30,000 years. The proportion of .^(14)C to .^(12)C living matter is 1:10^(12). Which fo the following option is correct?
Answer» In LIVING organisms, circulation of`.^(14)C` from atmosphere is high so the carbon content is constant in organism Carbon dating can be USEDTO find out the AGE of earth crust and rocks Radioactive absorption due to cosmic radiation is equal to the rate of radioactivedecay, hence the carbon content REMAINSCONSTANT in living organism Carbon dating cannot be used to determine concentration of `.^(14)C` in dead beings. Solution :In living organism, `.^(14)C` content is constant (not carbon content) as the rate of absorption of `c^(14)` is equal to rate of DISINTEGRATION of `.^(14)C`. Carbon dating can be used to fing out the age of organic materic only .(not for finding the age of earth crust and rocks made of inorganic material)

Discussion

11.	Copper wire test of halogens is known as :
Answer» BEILSTEIN test Liebig's test Lassigne 's test Fusion test Answer :A

Discussion

12.	Copper wire test of halogen is known as :
Answer» Liebig's TEST LASSAIGNE's test Fusion test Beilstein's test SOLUTION :N//A

Discussion

13.	Copper vessel is used as electrolytic cell in the preparation of F_(2) . It is because
Answer» Copper is a CHEAP metal It is a good conductor of electricity Cu does not REACT with `F_(2)` Cu reacts with `F_(2)`and forms `CuF_(2)` which acs as a protective layer and prevents the further attack Answer :D

Discussion

14.	Which compound is formed when excess of KCN is added to an aqueous solution of copper sulphate
Answer» `K_2[CU(CN)_4]` `K_3[Cu(CN)_4]` `K_3[Cu(CN)_6]` `[Cu(CN)_2]` ANSWER :B

Discussion

15.	Copper sulphate solution cannot be stored in a vessel made up of: Zinc,Glass,Copper,Plastic.
Answer» Zinc Glass Copper Plastic Answer :A

Discussion

16.	Copper sulphate solution absorbs red colour form white light. Why?
Answer» SOLUTION :When white light is passed through COPPER SULPHATE solution, the unpaired d-electron of copper undergoes d-d transition absorbing the energy of red coloured radiation.

Discussion

17.	Copper sulphate pentahydrate on heating to 423 K gives :
Answer» `CuSO_(4). H_(2)O` `CuSO_(4)` `CuSO_(4). 3H_(2)O` `CuO+SO_(2)` Answer :B

Discussion

18.	Copper sulphate solution (250 mL) was electrolysed using a platinum anode and copper cathode. A constant current of 2 mA was passed for 16 minutes. It was found that after electrolysis the absorbance of the solution was reduced to 50% of its original value. Calculate the concentration of copper sulphate in the solution to begin with.
Answer» SOLUTION :INITIAL mole of `CuSO_4` per 250 ml `= 2 xx` mole of `CuSO_4` lost 2 x mol of CU deposited `7.958 xx 10^(-5) M`

Discussion

19.	Copper sulphate is dissolved in water containing…. For making bordeaux mixture.
Answer» NaOH KCN `CA(OH)_(2)` All of these Solution :BORDEAUX MIXTURE is a fungicide obtained by mixing `Ca(OH)_(2) and CuSO_(4)`

Discussion

20.	Copper sulphate is prepared by blowing a current of air through copper scrap and dilute H_(2)SO_(4). Dilute HNO_(3) is also added:
Answer» to oxidize copper to `Cu^(2+)` which then form `CuSO_(4)` with DILUTE `H_(2)SO_(4)` to oxidise `Fe^(2+)` to ion (III) sulphate, which remains in solution after crystallisation of `CuSO_(4)` to speed up the ionisation of `H_(2)SO_(4)` to give `SO_(4)^(2-)` ions Which COMBINES with `H_(2)SO_(4)` to give a very STRONG oxidising mixture and oxidise Cu to `Cu^(2+)` Answer :A

Discussion

21.	Copper sulphate is not stored in aluminium container because
Answer» COPPER gets REDUCED copper gets oxidised aluminiumgets reduced copper SULPHATE become deliquescent Solution :`E_("red")^(0) CU gt E_("red")^(0)Al`

Discussion

22.	Copper sulphate is commercially made from copper scrap by :
Answer» DISSOLVING in hot CONCENTRATED SULPHURIC acid Action of dilute sulphuric acid and air Heating with sodium sulphate Heating with SULPHUR Answer :B

Discussion

23.	Copper sulphate dissolves in excess of KCN to give
Answer» `[Cu(CN)_(4)]^(2-)` `Cu(CN)_(2)` `CuCN` `[Cu(CN)_(4)]^(3-)` Solution :KCN first reduces CUPRIC IONS to cuprous ions which are precipitated as cuprous cyanide. This REACTS with excess of `CN^(-)` to form SOLUBLE four-coordinated complex `[Cu(CN)_(4)]^(3-)` which is tetrahedral in shape. `2Cu^(2+)+4CN^(-)rarr2Cu^(+)CN^(-)+underset("Cyanogen")((CN)_(2))` `CuCN+3CN^(-)rarr[Cu(CN)_(4)]^(3-)` or `3KCN+CuCNrarrK_(3)[Cu(CN)_(4)]`

Discussion

24.	Copper sulphate dissolves in excess of KCN to give :
Answer» `[Cu(CN)_(4)]^(3-)` `[Cu(CN)_(4)]^(2-)` `Cu(CN)_(2)` CuCN Solution :`[Cu(CN)_(4)]^(3-)` is formed

Discussion

25.	Copper sub-group ppt. and arsenic salt -group ppt. are sepeated using (a) ____.
Answer» ANSWER :YAS or `NAOH`

Discussion

26.	Copper, silver and gold are collectively called as "…............."metals.
Answer» ANSWER :COINAGE

Discussion

27.	Copper sulphate solution ______ stored in an iron vessel.
Answer» SOLUTION :cannot be

Discussion

28.	Copper reduces NO_3^(-) into NO and NO_2 depending upon concentration of HNO_3 in solution . Assuming [Cu^(2+)] = 0.1 M, and P_(NO) = P_(NO_2) = 10^(-3) bar . At which concentration of HNO_3 . Thermodynamic tendency for reduction of NO_3^(-)into NO and NO_2 by copper is same ? Given : E_(Cu^(2+)\|Cu)^(@) = + 0.34 V , E_(NO_3^(-)\|NO)^(@) = + 0.96 V , E_(NO_3^(-)\|NO_2)^(@) = + 0.79 V
Answer» <P>`10^(1.32) M ` `10^(0.56) M` `10^(0.66) M` None Solution :`3Cu^(0) + 2NH_3^(-) + 8H^(+) to 3Cu^(+2) + 2NO + 4H_2O` ` E^(0) =E_("cathode") -E_("anode") = E_(NO_3^(-) // NO ) - E_(Cu^(+2)// NO_2) -E_(Cu^(+2)//Cu) = 0.96 - 0.34 = 0.02 ` ` E_("CELL") = E^(0) -(0.059)/(n) log""([Cu^(+2)]^(3) P_(NO)^(2))/([H^(+)]^(8)) = 0.62 - (0.059)/(6) log_(10)""((0.1)^(3)(10^(-3)^(2)))/([H^(+)]^(8))` `Cu + 2NO_3^(-) + 4H^(+) to Cu^(+2) + 2NO_2 + 2H_2O , E^(0) =E_(NO_3^(-) // NO_2)^(0)-E_(Cu^(+2)//Cu) = 0.79 - 0.34 = 0.45 ` `E_("cell")^(11) = E^(0) -(0.059)/(2) log ""([Cu^(+2)]P_(NO_2)^(2))/([H^(+)]^(4)) = 0.45 - (0.059)/(2) log""((0.1)(10^(-3))^(2))/([H^(+2)]^4), E_("cell")=E_("cell")` Then `[H^(+)] = 10^(1.32)`

Discussion

29.	Copper reduces NO_3^- into NO and NO_2 depending upon conc of HNO_3 in solution. Assuming [Cu^(2+)] =0.1M, and P_(NO)=P_(NO_2)=10^(-3)atm and using given data answer the following questions. E_(Cu^(2+)//Cu)^0=+0.34 volt E_(NO_3^-//NO)^0=+0.96 volt E_(NO_3^-//NO_2)^0=+0.79 volt at 298K (RT)/F(2.303)=0.06 volt At what HNO_3 concentration thermodynamic tendency for reduction of NO_3 into NO and NO_2 by copper is same ?
Answer» `10^(1.23)M` `10^(0.56)M` `10^(0.66)M` `10^(0.12)M` ANSWER :C

Discussion

30.	Copper reduces:
Answer» Na Al Mg None Answer :D

Discussion

31.	Copperreduces
Answer» AL NA MG None Answer :D

Discussion

32.	Copper react with conc. H_2SO_4 to gives
Answer» `CuSO_(4)+H_(2)` `CuSO_(4)+SO_(2)+H_(2O` `CuSO_(4)+S` `CuSO_(4)+O_(2)` Answer :B

Discussion

33.	Copper reduces
Answer» Na Al Mg None Answer :D

Discussion

34.	Copper pyrites , the chief ore of copper , is chemically :
Answer» `Cu_2S` `CuFeS_2` `CuCO_3.Cu(OH)_2` `Cu_2O` ANSWER :B

Discussion

35.	Copper pyritesore is concentrated by
Answer» Electromagneticmethod Gravityseparation method Frothfloatation method All the abovemethods Answer :C

Discussion

36.	Copper pyrites is roasted in a current of air of remove
Answer» SULPHUR and FEO FeO only ARSENIC and FeO Sulphur and Arsenic Solution :EXTRACTION of COPPER

Discussion

37.	Copper pyrites ore is concentrated by
Answer» ELECTROMAGNETIC method Gravity method Froth FLOATATION PROCESS All Answer :C

Discussion

38.	Copper pyrite and zinc blende are purified by……..
Answer» GRAVITY SEPARATION process Froth FLOATATION process Hand picking None of the above Answer :B

Discussion

39.	Copper oxide was prepared by the following methods : (a) In one case, 1.75 g of the metal were dissolved in nitric acid and igniting the residual copper nitrate yielded 2.19 g of copper oxide. (b) In the second case, 1.14 g of metal dissolved in nitric acid were precipitated as copper hydroxide by adding caustic alkali solution. The precipitated copper hydroxide after washing, drying and heating yielded 1.43 g of copper oxide. (c) In the third case, 1.45 g of copper when strongely heated in a current of air yielded 1.83 g ofcopper oxide. Show that the given data illustrate the law of constant composition.
Answer» Solution :Step 1. In the FIRST experiment. 2.19 g of copper OXIDE contained 1.75 g of Cu. `therefore"100 g of copper oxide contained Cu"=(1.75)/(2.19)xx100=79.91g`, i.e., `%" of Cu"= 79.91` Step 2. In the second experiment. 1.43 g of copper oxide contained 1.14 g of copper `therefore"100 g of copper oxide contained Cu"=(1.14)/(1.43)xx100=79.72g`, i.e., `%" of Cu"=79.72` Step 3. In the third experiment. 1.83 g of copper oxide contained 1.46 g of copper `therefore"100 g of copper oxide contained Cu"=(1.46)/(1.83)xx100=79.78g`, i.e., `%" of Cu"=79.78` THUS, the percentage of copper oxide derived from all the three exkperiments is nearly the same. Hence the above DATA illustrate the law of constant COMPOSITION.

Discussion

40.	Copper nitrate on strongly heating gives:
Answer» Cu Cupric oxide Cuprous oxide Cupric nitrate Answer :B

Discussion

41.	Copper metal of high purity is obtained by :
Answer» Carbon reduction HYDROGEN reduction ELECTROLYTIC method Thermite process Answer :C

Discussion

42.	Copper metal obtained from Bessemer converter is known as ____.
Answer» SOLUTION :BLISTERED COPPER.

Discussion

43.	Copper metal is not used:
Answer» In TAPS and WATER connections As an alloy in high SPEED drills In electric motor coils In BRASS utensils Answer :B

Discussion

44.	Copper metal has a face-centred cubic structure with unit cell length equal to 0.361 nm. Picturing copper ions in contact along the face diagonal, find the apparent radius of a copper ion.
Answer» SOLUTION :0.128 NM

Discussion

45.	Copper metal has a face-centred cubic structure with the unit-cell length equal to 0.361 nm. Picturing copper ions in contact along the face diagonal, what is the apparent radius of a copper ion?
Answer» SOLUTION :For a face-centred CUBE, we have RADIUS `=(SQRT(2)a)/4 = (sqrt(2) xx 0.361)/4 nm = 0.128 nm`

Discussion

46.	Copper metal has a face-centred cubic structure with the unit cell length equal to 0.361 nm. Picturing copper ions in contact along the face diagonal,The apparent radius of a copper ion is- (A) 0.128(B) 1.42 (C) 3.22(D) 4.22
Answer» Solution : (A) For a face-centred cube, we have, RADIUS`=(sqrt(2A))/(4)=(sqrt(2)xx0.361)/(4)` nm=0.128.

Discussion

47.	Copper metal dissolves in an aqueous solution of silver nitrate, imparting it a blue colour. This is because
Answer» CU is oxidized to `Cu^(+)` ions Cu is oxidized to `Cu^(2+)` ions AG is displaced IRON solution Ag-ions are oxidized to Ag Solution :`E_("red")^(0) Cu GT E_("red")^(0)Ag`

Discussion

48.	Copper metal crystallizes in face-centred cubic arrangement and surface of adjacent atoms along the edge of unit cell are 106 picometre apart. Determine the density of metal. Atomic mass of copper metal is 63.5 u.
Answer» Solution : According to the given information, a view of one FACE of the UNIT cell will be as shown below. In FCC: `4sqrt(2a)` The given distance is a -`2r=a-(a)/(SQRT(2))` `=a[(sqrt(2)-1)/(sqrt(2))]`=106 pm `IMPLIES`Density `(rho)=(4xx63.5)/(6.023xx10^(23)(3.62xx10^(-8))^(3)` `=8.89 g//cm^(3)`

Discussion

49.	Copper metal can be prepared by roasting copper ore, which contain cuprite (Cu_(2)S) and copper sulfide. (CuS) Cu_(2)S (s) + O_(2) (g) rarr 2Cu (s) + SO_(2) (g) CuS (s) + O_(2) (g) rarr Cu (s) + SO_(2) (g) If ore contains 14.6% impurity in addition to a mixture of CuS and Cu_(2)S. Heating 100 gm of mixture produces 70 gm of Cu metal with 90% purity. [Cu = 63] Percentage (By mass ) of CuS in the sample is :
Answer» 0.095 0.38 0.19 0.57 Solution :% by MASS of `CUS = (0.4 xx 95 xx 100)/(100) = 38%`

Discussion

50.	Copper metal can be prepared by roasting copper ore, which contain cuprite (Cu_(2)S) and copper sulfide. (CuS) Cu_(2)S (s) + O_(2) (g) rarr 2Cu (s) + SO_(2) (g) CuS (s) + O_(2) (g) rarr Cu (s) + SO_(2) (g) If ore contains 14.6% impurity in addition to a mixture of CuS and Cu_(2)S. Heating 100 gm of mixture produces 70 gm of Cu metal with 90% purity. [Cu = 63] Percentage (By mass) of sulphur in the sample is :
Answer» 0.448 0.2 0.224 0.4 Solution :`{:(Cu_(2)S,+,O_(2) rarr,2Cu,+,SO_(2),),(a mol,,,2 a mol,,,),(CuS,+,O_(2) rarr,Cu,+,SO_(2),),(b mol,,,(b mol),,,):}` `a xx 158 + b xx 95 = 85.4` …(i) `(2A + b) xx 63 = (70 xx 90)/(100) = 63` `2a + b = 1` …(ii) `a = 0.3, b = 0.4` % by mass of SULPHUR in sample `= ((0.3 + 0.4) 32 xx 100)/(100)` `= 22.4 %`

Discussion

Explore topic-wise InterviewSolutions in Current Affairs.

Correct decreasing order of acidity of oxides is

Correct combination for the preparation of Meoverset(18)OH will be :

Correct coombination which gives at last two organic compounds having underset(.)O^(18) in it after propanation :

CORRECT combination among the following is

Correct atomic size is :-

Correct and rewrite the statement---- Ravi, Beas river dispute was resolved between Himachal Pradesh, Punjab and Uttarakhand.

Correct among the following

Correct acidic strength of the following carboxylic acids A) C_(6) H_(5) COOH B) o-NO_(2) (C_(6) H_(4)) COOH C) p- NO_(2) (C_(6) H_(4)) COOH D) m- NO_(2) (C_(6) H_(4)) COOH

Copper wire test of halogens is known as :

Copper wire test of halogen is known as :

Copper vessel is used as electrolytic cell in the preparation of F_(2) . It is because

Which compound is formed when excess of KCN is added to an aqueous solution of copper sulphate

Copper sulphate solution cannot be stored in a vessel made up of: Zinc,Glass,Copper,Plastic.

Copper sulphate solution absorbs red colour form white light. Why?

Copper sulphate pentahydrate on heating to 423 K gives :

Copper sulphate is dissolved in water containing…. For making bordeaux mixture.

Copper sulphate is prepared by blowing a current of air through copper scrap and dilute H_(2)SO_(4). Dilute HNO_(3) is also added:

Copper sulphate is not stored in aluminium container because

Copper sulphate is commercially made from copper scrap by :

Copper sulphate dissolves in excess of KCN to give

Copper sulphate dissolves in excess of KCN to give :

Copper sub-group ppt. and arsenic salt -group ppt. are sepeated using (a) ____.

Copper, silver and gold are collectively called as "…............."metals.

Copper sulphate solution ______ stored in an iron vessel.

Copper reduces:

Copperreduces

Copper react with conc. H_2SO_4 to gives

Copper reduces

Copper pyrites , the chief ore of copper , is chemically :

Copper pyritesore is concentrated by

Copper pyrites is roasted in a current of air of remove

Copper pyrites ore is concentrated by

Copper pyrite and zinc blende are purified by……..

Copper nitrate on strongly heating gives:

Copper metal of high purity is obtained by :

Copper metal obtained from Bessemer converter is known as ____.

Copper metal is not used:

Copper metal has a face-centred cubic structure with unit cell length equal to 0.361 nm. Picturing copper ions in contact along the face diagonal, find the apparent radius of a copper ion.

Copper metal has a face-centred cubic structure with the unit-cell length equal to 0.361 nm. Picturing copper ions in contact along the face diagonal, what is the apparent radius of a copper ion?

Copper metal has a face-centred cubic structure with the unit cell length equal to 0.361 nm. Picturing copper ions in contact along the face diagonal,The apparent radius of a copper ion is- (A) 0.128(B) 1.42 (C) 3.22(D) 4.22

Copper metal dissolves in an aqueous solution of silver nitrate, imparting it a blue colour. This is because

Copper metal crystallizes in face-centred cubic arrangement and surface of adjacent atoms along the edge of unit cell are 106 picometre apart. Determine the density of metal. Atomic mass of copper metal is 63.5 u.