94420 + Interview Questions in Chemistry in Class 12

1.	Ferrous sulphate forms Turnbulls blue with:
Answer» KCN `NH_4SCN` `K_3[Fe(CN)_6]` `K_4[Fe(CN)_6]` Answer :C

Discussion

2.	Ferrous sulphate forms Turn bull's blue with
Answer» KCN `NH_(4)SCN` `K_(3)[Fe(CN)_(6)]` `K_(4)[Fe(CN_(6))]` Solution :`3FeSO_(4)+K_(3)[Fe(CN)_(6)]toFe_(3)[Fe(CN)_(6)]_(2)+3K_(2)SO_(4)`, Ferraferric cyanide

Discussion

3.	Ferrous salts slowly convert to ferric salts on exposure to air. Why?
Answer» Solution :`Fe^(2+)` state is OXIDIZED to `Fe^(3+)` which is more stable ELECTRONIC configuration i.e., `3d^(5)`-half FILLED configuration

Discussion

4.	Ferrous ion changes to 'X' ion, on reacting with acidified hydrogen peroxide. The number of d-electrons present in 'X' and its magnetic moment are
Answer» 6 and 6.93 B.M. 5 and 5.92 B.M. 5 and 4.9 B.M. 4 and 5.92 B.M. Solution : 5 and 5.92 B.M.

Discussion

5.	Ferromagnetismis maximum in
Answer» FE Ni CO None Solution :Ferromagnetism is MAXIMUM is Fe out of F,Co and Ni .

Discussion

6.	Ferrosilicon is used in steel industry as
Answer» A flux Scavenger of hydrogen A REDUCING agent Alloying agent Answer :D

Discussion

7.	Extent of Ferromagnetism is maximum in
Answer» fe `NI^(2+)` `CO_(3+)` C`Cu^(2+)` Answer :A

Discussion

8.	Ferromagnetism is exhibited only below
Answer» 842 K 1042 K 742 K 642 K Answer :B

Discussion

9.	Ferromagnetism arises becases of the sponteneous alignment of the magnetic moments due to unpaired electrons as
Answer» uparrowuparrowuparrowuparrowuparrow uparrowuparrowuparrowdownarrowdownarrow uparrowdownarrowuparrowdownarrow uparrowuparrowdownarrowuparrowuparrow Answer :A

Discussion

10.	Ferrochrome, an iron chromium alloy used in making stainless steel, is produced by reducing chromite (FeCr_(2)O_(4)) with coke : FeCr_(2)O_(4)(s) + 4C (s) rarr underset("Ferrochrome")(underbrace(Fe(s) + 2Cr(s))) + 4CO(s) (i) How many kilograms of chromium can be obtained by the reaction of 236 kg of chromite with an excess of coke ? (ii) How many litres of CO at 25^(@)C and 740 mm Hg are obtained as a by-product ?
Answer» Solution :(i) `FeCr_(2)O_(4)(s) + 4C(s) rarr Fe(s) + 2Cr(s) + 4CO(s)` 224 KG of chromite gives = 104 kg of Cr 236 Kg of chromite gives `= (104 XX 236)/(224)` kg of Cr = 109.57 kg Cr (ii) 224 kg chromite gives = 112 Kg CO Thus 236 kg chromite gives `= (112 xx 236)/(224)` kg CO `rArr` 118 kg CO = 4214.2857 mol. As PV = nRT T = 298 K `P = (740)/(760)` atm `therefore""V = (nRT)/(P) = (4214.28 xx 0.0821xx 298 xx 760)/(740)` `= 105.89 xx 10^(3)` litre

Discussion

11.	Ferrocene is diamagnetic in nature. According to valence bond theory the hybride state assumed by Fe in ferrocene is
Answer» `sp^2` `sp^3d^2` `d^2sp^3` `sp^3d` ANSWER :C

Discussion

12.	Ferromagnetic substances have
Answer» ZERO magneticmoment SMALL magnetic moment large magnetic moment any valueof magneticmoment ANSWER :C

Discussion

13.	Formula of ferrocene is:
Answer» `Fe(eta^5-C_5H_5)_2` `Fe(eta^2-C_5H_5)_2` `CR(eta^5-C_5H_5)_5` `Os(eta^5-C_5H_5)_2` ANSWER :A

Discussion

14.	Ferrocene is:
Answer» `Fe(eta^5-C_5H_5)_2` `Fe(eta^2-C_5H_5)_2` `CR(eta^5-C_5H_5)_5` `Os(eta^5-C_5H_5)_2` Answer :A

Discussion

15.	Ferrimagnetic substances lose ferrimagnetism on heating and become ______________
Answer» ANSWER :PARAMAGNETIC

Discussion

16.	Ferrimagnetic is converted into ferromagnetic at :
Answer» 300 K 400 K 600 K 850 K Answer :D

Discussion

17.	Ferric sulphate on heating gives:
Answer» `SO_2` and `SO_3` `SO_3` only `SO_3` only S only Answer :C

Discussion

18.	Ferric oxide in furnance is reduced by
Answer» C `H_2` CO `CO_2` ANSWER :C

Discussion

19.	Ferric oxide in blast furnance is reduced by :
Answer» C `H_2` CO `CO_2` ANSWER :C

Discussion

20.	Ferric oxide crystallises in a hexagonal close packed array of oxide ions with two out of every three octahedral holes occupied by ferric ions. Derive the formula of the ferric oxide.
Answer» SOLUTION :Number of oxide ION per unit cell = 6 `therefore` Total number of OCTAHEDRAL VOIDS = 6 Number of ferric ion present `= 2/3 xx 6 = 4` `therefore ` Ratio of `Fe^(3+)` ions to `O_("ions")^(2-)= 4 : 6 = 2:3` Hence formula of oxide is `Fe_2O_3`

Discussion

21.	Ferric oxide crystallises in a hexagonal close-packed array of oxide ions with two out of every three octahedral holes occupied by ferric ions. Derive the formula of the ferric oxide.
Answer» Solution :Let the number of `O^(2-)` IONS in the packing= N Number of octahedral holes (voids) =N Voids occupied by `FE^(3+)= (2N)/(3)` Ratio of `Fe^(3+) : O^(2-)= (2N)/(3): N` `=2:3` Formula of ferric OXIDE = `Fe_(2)O_(3)`

Discussion

22.	Ferric ion forms a prussiann blue coloured ppt. due to
Answer» `K_(4)Fe(CN)_(6)` `Fe_(4)[Fe(CN)_(6)]_(3)` `KMnO_(4)` `Fe(OH)_(3)` Solution :`4FeCl_(3)++3K_(4)[Fe(CN)_(6)]tounderset("Prussian Blue colour")(Fe_(4)[Fe(CN)_(6)])+12KCl`

Discussion

23.	Ferric ion forms a prussian blue coloured precipitate with K_(4)[Fe(CN)_(6)]a due to the formation of
Answer» `K_(3)Fe(CN)_(6)` `Fe_(4)[Fe(CN)_(6)]_(3)` `Fe(OH)_(3)` `KFE[Fe(CN)_(6)]` SOLUTION :`Fe_(4)[Fe(CN)_(6)]_(3)`

Discussion

24.	Ferric ion forms a prussian blue precipitate due to the formation of
Answer» `K_(4)[FE(CN)_(6)]` `K_(3)[Fe(CN)_(6)]` `Fe(CNS)_(3)` `Fe_(4)[Fe(CN)_(6)]_(3)` Solution :Prussian blue precipitate is `Fe_(4)[Fe(CN)_(6)]_(3)`

Discussion

25.	Ferric hydroxide sol is prepared by
Answer» treating ferric chloride with dilute sodium hydroxide SOLUTION treating ferric chloride with dilute ammonium hydroxide solution adding ferric chloride solution to BOILING water any onhe of the above methods Answer :C

Discussion

26.	Ferric hydroxide sol is positively charged colloid. The coagulating power of NO_3^-, SO_4^(2-) and PO_4^(3-) ions would be in the order
Answer» `NO_3^(-) GT SO_4^(2-) gt PO_4^(3-)` `SO_4^(2-) gt NO_3^(-) gt PO_4^(3-)` `PO_4^(3-) gt SO_4^(2-) gt NO_3^-` `NO_3^(-) = SO_4^(2-) =PO_4^(3-)` ANSWER :C

Discussion

27.	Ferric hydroxide sol is more readily coagulated by Na_3PO_4 in comparison to KCl.
Answer» Solution :Ferric hydroxide SOL is positively charged and to CAUSE its coagulation, ions carrying negative charge are needed. Since `PO_4^(3-)` ions have HIGHER negative charge than `Cl^–` ions therefore, `Na_3PO_4` COAGULATES the ferric hydroxide sol most efficiently.

Discussion

28.	Ferric hydroxide sol can be prepared from freshly perpared ferric hydroxide precipitate. It can also be prepared by adding ferric chloride solution to boilling water. In both cases the sol particles are positively charged. Name the above two methods of preparation of ferric hydroxide sol.
Answer» ANSWER :PEPTIZATION and HYDROLYSIS RESPECTIVELY.

Discussion

29.	Ferric chloride forms both positively and negatively charged sols. Explain.
Answer» Solution :When `Fecl_(3)` is added to excess of HOT water , a positively chargedsol of hydrated FERRIC oxide is FORMED due to adsorption of ferric ions. `Fe_(2)O_(3).xH_(2)O //Fe^(3+)`is a positively charged sol. When `FeCl_(3)` is added to alkali solution , a NEGATIVELY charged sol of ferric oxide is formed due to adsorption of hydroxyl ions. `Fe_(2)O_(3).xH_(2)O //OH^(-)` is a negatively charged sol.

Discussion

30.	Ferric chloride on rubbing to a bleeding wound causes
Answer» COAGULATION peptisation emulsification de-emulsification Answer :A

Discussion

31.	Ferric chloride is applied to stop bleeding due to cut because :
Answer» `Fe^(3+)` ion Caogulates BLOOD which is a negatively charged sol. `Fe^(3+)` ion Coagulates blood WHICHIS a POSITIVELY charged sol. `Cl^(-)` ion Coagulates blood which is a positively charged sol. `Cl^(-)` ion Coagulates blood which is a negatively charged sol. Solution :`Fe^(3+)` ion coagulate the SOLUBLE PROTEIN ( Present in blood plasma ) which are negatively charged.

Discussion

32.	Ferric chloride is applied to stop bleeding due to a cut because :
Answer» `Fe^(3+)` ion coagulates blood which is a negatively CHARGED sol. `Fe^(3+)` ion coagulates blood which is a POSITIVELY charged sol. `Cl^(-)` ion coagulates blood which is positively charged sol. `Cl^(-)` ion coagulates blood which is a negatively charged sol. Solution :`Fe^(3+)` ions coagulate the solble proteins (present in blood plasma) which are negetively charged. (REMEMBER that when a blood vessel breaks, bleeding stops by itself afte rsometime. It is due to colustering together of platelest (blood particles) to from a plug).

Discussion

33.	Ferric chloride (neutral) reacts with catechol to give :
Answer» GREEN COLOUR BLUE colour BLACK colour VIOLET colour. Answer :A

Discussion

34.	Ferric chloride is applied to stop bleeding because
Answer» `Fe ^(3+)` ions coagulate blood which is a negatively CHARGED sol. `Fe Cl_(3)` reacts with the CONSTITUENTS of blood to FORM a complex. `Cl ^(+)` ions coagulate blood which is a positively charged sol. Blood absorbs `FECL _(3).` Answer :A

Discussion

35.	Ferric alum has the composition (NH_(4))_(2)SO_(4). Fe_(2)(SO_(4)).xH_(2)O.x is
Answer» 7 24 6 15 Solution :Ferric ALUM is `(NH_(4))_(2) SO_(4). Fe_(2)(SO_(4))_(3).24H_(2)O`

Discussion

36.	Ferric chloride is applied to stop bleeding because:
Answer» `FE^(3+)` ion coagulates blood, which is a NEGATIVELY charged SOL `Fe^(3+)` ion coagulates blood, which is a POSITIVELY charged sol `Cl_(–)` coagulates blood, which is a positively charged sol `Cl^(–)` ion coagulates blood, which is a negatively charged sol Answer :A

Discussion

37.	Ferric alum gives red colour with NH_(4)SCN dueto formation of
Answer» `AI(SCN)_(3)` `[Fe(SCN)_(3)]^(THETA)` `Fe(SCN)_(3)` `Fe(SCN)_(3)]^(2+)`` ANSWER :C

Discussion

38.	Ferric alum is the indicatein the tatration of Ag^(o+) with SCN^(Θ) when (a)_____colour apears of the end point .
Answer» ANSWER :RED

Discussion

39.	Ferric alum does not form precipitate with.
Answer» NaOH `BaCl_(2)` `Na_(2)CO_(3)` `H_(2)S" GAS"` Solution :For maximum volume of 3M HCl solution 2M, 1L HCl solution should be USED completely. `M_(1)V_(1)+M_(2)V_(2)=M_(F)V_(f)""2xx1+5xxV=3xx(1+V),V=(1)/(2)L,V_(f)=(3)/(2)l`

Discussion

40.	table salt is:
Answer» HF `KHF_2` NACL `KClO_3` ANSWER :B

Discussion

41.	Fermentation of sugar with yeast gives :
Answer» `CH_3OH` HCHO `C_2H_5OH` `CH_3CH_2CH_2OH` ANSWER :C

Discussion

42.	Fermentationis an//a :
Answer» ENDOTHERMIC REACTION exothermic reaction polymerisation reaction condensation reaction ANSWER :B

Discussion

43.	Fermentation of starch solution to ethyl alcohol does not require
Answer» Diastase Invertase Maltase Zymase Answer :B

Discussion

44.	Fermentation of starch to give alcohol takes place in presence of:
Answer» ENZYMES `CO_2` AIR `N_2` ANSWER :A

Discussion

45.	Fermentation is an
Answer» ENDOTHERMIC REACTION Exothemic reaction Reversible reaction NONE of above Answer :B

Discussion

46.	Fermentation is a reaction called
Answer» Endothermic EXOTHERMIC Isotemperature Reversible SOLUTION :FERMENTATION is exothermic REACTION.

Discussion

47.	Fermentation is :
Answer» Exothermic Endothermic Reversible None Answer :A

Discussion

48.	Fe(OH)_(3) can be separated from Al(OH)_(3) by the addition of
Answer» NACL SOLUTION Dil. HCl solution NaOH solution `NH_(4)Cl` and `NH_(4)OH` Solution :Due to common ion effect of `NH_(4)^(+)`, CONCENTRATION of `OH^(-)` decreases, as `K_(sp)Fe(OH)_(3) LT K_(sp)Al(OH)_(3)` thus `Fe(OH)_(3)` get precipitated first.

Discussion

49.	Fe(OH)_3 can be separated from Al(OH)_3 by the addition of
Answer» Dil.HCl NaCl solution NaOH solution `NH_(4)Cl`+NHOH Solution :NaOH DISSOLVES `Al(OH)_(3)` ppt. forming `NaAlO_2` LEAVING behind `Fe(OH)_(3)` as residue. `Al(OH)_(3)(s)+NaOH (aq) toNaAlO_(2) (aq)+2H_(2)O(l)`

Discussion

50.	Fe(OH)_(3) can be separated from Al(OH)_(3) by addition of:
Answer» DIL. HCI NACL solution NaOH solution `NH_(4)CI` and `NH_(4)OH` Answer :C

Discussion

Explore topic-wise InterviewSolutions in Current Affairs.

Ferrous sulphate forms Turnbulls blue with:

Ferrous sulphate forms Turn bull's blue with

Ferrous salts slowly convert to ferric salts on exposure to air. Why?

Ferrous ion changes to 'X' ion, on reacting with acidified hydrogen peroxide. The number of d-electrons present in 'X' and its magnetic moment are

Ferromagnetismis maximum in

Ferrosilicon is used in steel industry as

Extent of Ferromagnetism is maximum in

Ferromagnetism is exhibited only below

Ferromagnetism arises becases of the sponteneous alignment of the magnetic moments due to unpaired electrons as

Ferrocene is diamagnetic in nature. According to valence bond theory the hybride state assumed by Fe in ferrocene is

Ferromagnetic substances have

Formula of ferrocene is:

Ferrocene is:

Ferrimagnetic substances lose ferrimagnetism on heating and become ______________

Ferrimagnetic is converted into ferromagnetic at :

Ferric sulphate on heating gives:

Ferric oxide in furnance is reduced by

Ferric oxide in blast furnance is reduced by :

Ferric oxide crystallises in a hexagonal close packed array of oxide ions with two out of every three octahedral holes occupied by ferric ions. Derive the formula of the ferric oxide.

Ferric oxide crystallises in a hexagonal close-packed array of oxide ions with two out of every three octahedral holes occupied by ferric ions. Derive the formula of the ferric oxide.

Ferric ion forms a prussiann blue coloured ppt. due to

Ferric ion forms a prussian blue coloured precipitate with K_(4)[Fe(CN)_(6)]a due to the formation of

Ferric ion forms a prussian blue precipitate due to the formation of

Ferric hydroxide sol is prepared by

Ferric hydroxide sol is positively charged colloid. The coagulating power of NO_3^-, SO_4^(2-) and PO_4^(3-) ions would be in the order

Ferric hydroxide sol is more readily coagulated by Na_3PO_4 in comparison to KCl.

Ferric hydroxide sol can be prepared from freshly perpared ferric hydroxide precipitate. It can also be prepared by adding ferric chloride solution to boilling water. In both cases the sol particles are positively charged. Name the above two methods of preparation of ferric hydroxide sol.

Ferric chloride forms both positively and negatively charged sols. Explain.

Ferric chloride on rubbing to a bleeding wound causes

Ferric chloride is applied to stop bleeding due to cut because :

Ferric chloride is applied to stop bleeding due to a cut because :

Ferric chloride (neutral) reacts with catechol to give :

Ferric chloride is applied to stop bleeding because

Ferric alum has the composition (NH_(4))_(2)SO_(4). Fe_(2)(SO_(4)).xH_(2)O.x is

Ferric chloride is applied to stop bleeding because:

Ferric alum gives red colour with NH_(4)SCN dueto formation of

Ferric alum is the indicatein the tatration of Ag^(o+) with SCN^(Θ) when (a)_____colour apears of the end point .

Ferric alum does not form precipitate with.

table salt is:

Fermentation of sugar with yeast gives :

Fermentationis an//a :

Fermentation of starch solution to ethyl alcohol does not require

Fermentation of starch to give alcohol takes place in presence of:

Fermentation is an

Fermentation is a reaction called

Fermentation is :

Fe(OH)_(3) can be separated from Al(OH)_(3) by the addition of

Fe(OH)_3 can be separated from Al(OH)_3 by the addition of

Fe(OH)_(3) can be separated from Al(OH)_(3) by addition of: