94420 + Interview Questions in Chemistry in Class 12

1.	Borax on heating with cobalt oxide forms a blue bead of :
Answer» `CO(BO_2)_2` `CoBO_2` `Co_3(BO_3)_2` `Na_3Co(BO_3)_2` ANSWER :A

Discussion

2.	Borax [Na_(2)B_(4)O_(7).10H_(2)O] when heated on platinum loop it gives a dark transparent glass like bead. The hot bead is dipped in the salt till it reacts with transition metal oxide. It produces characteristic bead of meta borate. {:("Colour of the bead","lon"),("(a) Blue green or light blue",Cu^(+2)),("(b) Yellow",Fe^(+2)or Fe^(+3)),("(c) Green",Cr^(+3)),("(d) Violet",Mn^(+2)),("(e) Dark blue",Co^(+2)),("(f) Brown",Ni^(+2)):} The colour of bead Ni(BO_(2))_(2) is
Answer» Green Brown Violet Blue Answer :B

Discussion

3.	Borax [Na_(2)B_(4)O_(7).10H_(2)O] when heated on platinum loop it gives a dark transparent glass like bead. The hot bead is dipped in the salt till it reacts with transition metal oxide. It produces characteristic bead of meta borate. {:("Colour of the bead","lon"),("(a) Blue green or light blue",Cu^(+2)),("(b) Yellow",Fe^(+2)or Fe^(+3)),("(c) Green",Cr^(+3)),("(d) Violet",Mn^(+2)),("(e) Dark blue",Co^(+2)),("(f) Brown",Ni^(+2)):} The flame used in Boram Bead test is
Answer» Reducing Oxidising Both (1) & (2) NEITHER (1) nor (2) ANSWER :C

Discussion

4.	Borax [Na_(2)B_(4)O_(7).10H_(2)O] when heated on platinum loop it gives a dark transparent glass like bead. The hot bead is dipped in the salt till it reacts with transition metal oxide. It produces characteristic bead of meta borate. {:("Colour of the bead","lon"),("(a) Blue green or light blue",Cu^(+2)),("(b) Yellow",Fe^(+2)or Fe^(+3)),("(c) Green",Cr^(+3)),("(d) Violet",Mn^(+2)),("(e) Dark blue",Co^(+2)),("(f) Brown",Ni^(+2)):} Glassy bead is of
Answer» `B_(2)O_(3)+NaBO_(2)` `Na_(3)BO_(3)` `Na_(2)B_(4)O_(7)` `SiO_(2)` Answer :A

Discussion

5.	Borax [Na_(2)B_(4)O_(7).10H_(2)O] when heated on platinum loop it gives a dark transparent glass like bead. The hot bead is dipped in the salt till it reacts with transition metal oxide. It produces characteristic bead of meta borate. {:("Colour of the bead","lon"),("(a) Blue green or light blue",Cu^(+2)),("(b) Yellow",Fe^(+2)or Fe^(+3)),("(c) Green",Cr^(+3)),("(d) Violet",Mn^(+2)),("(e) Dark blue",Co^(+2)),("(f) Brown",Ni^(+2)):} The hybridisation of B in Borax is
Answer» `sp^(2)` `sp^(3)` Both (1) & (2) sp Answer :C

Discussion

6.	Borax is prepared by treating colemanite with :
Answer» `NaNO_3` `NACL` `Na_2CO_3` `NaHCO_3` ANSWER :C

Discussion

7.	Borax is ………………. In nature.
Answer» basic acidic amphoteric chemically inert Answer :A

Discussion

8.	Borax is converted into B by the following steps: Boraxoverset(I)toH_(3)BO_(3)overset(Delta)toB_(2)O_(3)overset(II)toB B I and I reagents are
Answer» ACID, AI acid, C acid, FE acid, Mg Answer :D

Discussion

9.	Borax is converted into B by steps Borax overset(1)to H_(3)BO_(3) overset(Delta) to B_(2)O_(3) overset(II)to B I and II reagents are
Answer» ACID, Al acid, C acid, Fe acid, MG ANSWER :D

Discussion

10.	Borax is a sodium salt of ……………… .
Answer» ANSWER :tetraboric ACID

Discussion

11.	Borax is :
Answer» `Na_2B_4O_7` `(Na_2B_4O_7).4H_2O` `(Na_2B_4O_7).7H_2O` `(Na_2B_4O_7).10H_2O` ANSWER :D

Discussion

12.	Borax is _____________
Answer» `Na_(2)[B_(4)O_(5)(OH)_(4)].8H_(2)O` `Na_(2)[B_(4)O_(5)(OH)_(6)].7H_(2)O` `Na_(2)[B_(4)O_(3)(OH)_(8)].6H_(2)O` `Na_(2)[B_(4)O_(2)(OH)_(10)].5H_(2)O` Answer :A

Discussion

13.	Borax heat test is given by
Answer» `Co^(2+)` `Zn^(2+)` `Cu^(2+)` ions `NI^(2+)` Solution :White salts or ions GIVING colourless HEATED do do not give borasx BEAD test ,Salts of `Cu^(2+),Cu^(2-)` and `Ni^(2+)` give borax bead test

Discussion

14.	Borax dissolves to give
Answer» `NAOH^(+) B_2 O_3` `NaOH^(+) B_2 H_` `NaOH^(+) H_3 B O_3` `NaOH^(+) HBO_2` ANSWER :C

Discussion

15.	Borax bead test is responded by :
Answer» DIVALENT metals Heavy metals Light metas Metals FORMING COLOURED metal-borates Answer :D

Discussion

16.	Borax bead test is not given by :
Answer» An ALUMINIUM salt A COBALT salt A COPPER salt A NICKEL salt Answer :A

Discussion

17.	Borax bead test is given by
Answer» `Co^(2+)` `ZN^(2+)` `Cu^(2+)` `Ni^(2+)` Solution :White salts or IONS giving colourless beads do not GIVE borax bead test. HENCE, (A), (C) and (D) are the CORRECT answers.

Discussion

18.	Borax bead test depends upon the formation of :
Answer» BORON oxide metal borides elemental boron metal META borates. Answer :D

Discussion

19.	Borax bead is responded generally by :
Answer» ALKALI METAL SALT ALKALINE EARTH metals p-block metal salt d-block metal salt Answer :D

Discussion

20.	Borax bead cannot be performed with which of the following salts
Answer» `CuCl_(2)` `FeCl_(2)` `CoS` `AlCl_(3)` SOLUTION :`NACL+K_(2)CrO_(7)+KSO_(4)rarrCrO_(2)Cl_(2)`(orange red ) `CrO_(2)Cl_(2)+NaOHrarrNa_(2)CrO_(4)("yellow")+NaCl` `Na_(2)CrO_(4)overset(H^(+))(rarr) Na_(2)Cr_(2)O_(7)`

Discussion

21.	Borate from green colour flame when burnt with (Conc. H_2SO_4+ ethanol). Green colour flame is obtained due to due to formation of
Answer» `(C_2H_5O)_3B` `(C_2H_5)_2BO_3` `(C_2H_5)_3B` A and C are CORRECT ANSWER :C

Discussion

22.	Borane is an electron deficient compound. It has only six valence eletons, so the boron atom lacks an octet. Acquiring an octet is the driving force for the unusual bonding structure found in boron compounds. As an electron deficient compound, BH_(3) is a strong electrophile, capable of adding to a double bond. This hydroboration of double bond is though to oC Cur in one step, with the boron atom adding to the less highly substituted end of the double bond. In transition state, the boron atom withdraws electrons from the pi bond and the carbon at theother end of the double bond acquires a partial positive charge. This positive charge is more stable on the more highly subsituted carbon atom. The second step is the oxidation of boron atom, removing it from carbon and replacing it with hydroxyl group by using H_(2)O_(2)//OH^(bar(..)). The simultaneous addition of boron and hydrogen to the double bond leads to a syn addition. Oxidation of the trialkyl borane replaces boron with a hydroxyl group in the same stereochemical position. Thus, hydroboration of alkenen is an example of steropecific reaction, in which different steroisomers of starting compounds react to give different steroisomers of the product. Y is :
Answer» both None of these SOLUTION :N//A

Discussion

23.	Borane is an electron deficient compound. It has only six valence eletons, so the boron atom lacks an octet. Acquiring an octet is the driving force for the unusual bonding structure found in boron compounds. As an electron deficient compound, BH_(3) is a strong electrophile, capable of adding to a double bond. This hydroboration of double bond is though to oC Cur in one step, with the boron atom adding to the less highly substituted end of the double bond. In transition state, the boron atom withdraws electrons from the pi bond and the carbon at theother end of the double bond acquires a partial positive charge. This positive charge is more stable on the more highly subsituted carbon atom. The second step is the oxidation of boron atom, removing it from carbon and replacing it with hydroxyl group by using H_(2)O_(2)//OH^(bar(..)). The simultaneous addition of boron and hydrogen to the double bond leads to a syn addition. Oxidation of the trialkyl borane replaces boron with a hydroxyl group in the same stereochemical position. Thus, hydroboration of alkenen is an example of steropecific reaction, in which different steroisomers of starting compounds react to give different steroisomers of the product. underset((ii)H_(2)O_(2)//OH^(bar(..)))overset((i)BH_(3)//THF)rarr "product". The product is
Answer» THREO CYCLIC alchohol Erythreo cyclic alcohol Optically active alchohol Both (B) and (C) SOLUTION :N//A

Discussion

24.	Boot polish is what type of colloid.
Answer» SOLUTION :Boot POLISH is a LIQUID in solid i.e. gels TYPE of COLLOID

Discussion

25.	Books, periodicals, magazines and calendars are printed in large numbers. Type metal used in printing presses as alphabet letter printing contains
Answer» Sulphur chromium lead copper Answer :C

Discussion

26.	Bones glow in the dark. This is due to:
Answer» the presence of red phosphorus conversion of WHITE P into red P slow combustion of white P in CONTACT with air conversion of red P into white P Answer :C

Discussion

27.	Bones glow in the dark, because:
Answer» They contain a SHINING material They contain red PHOSPHORUS White phosphorus changes into red phosphorus White phosphorus undergoes SLOW COMBUSTION with air. Answer :D

Discussion

28.	Bones glow in the dark because
Answer» They contains SHINING materials They contain red phosphorus WHITE phosphorus undergoes slow combustion in contact with air White phosphorus changes into red FORM Answer :C

Discussion

29.	Bone black is a polymorphic form of
Answer» PHOSPHORUS Sulphur Carbon Nitrogen Solution :Bone BLACK is the POLYMORPHIC form of phosphorus.

Discussion

30.	Bond type between O and B in BH_3 larr (OC_2H_5)_2 is:
Answer» COORDINATE covalent ionic hydrogen Answer :A

Discussion

31.	Bond present in O_2 molecule ls
Answer» `ppi-ppi` `ppi-dpi` `dpi-dpi` `dpi-Ppi` ANSWER :A

Discussion

32.	Bond present in benzene diazonium chloride are
Answer» only IONIC ionic, COVALENT and co-ordinate only covalent ionic and covalent Answer :B

Discussion

33.	Bond order of N_2^- anion is:
Answer» 3 2 2.5 1.5 Answer :C

Discussion

34.	Bond order normally gives idea of stability of a molecular species. All the molecules viz. H_(2) Li_(2) and B_(2) have the same bond order yet they are not equally stable. Their stability order is
Answer» `H_(2) GT B_(2) gt Li_(2)` `H_(2) gt Li_(2) gt B_(2)` `Li_(2) gt B_(2) gtH_(2)` `B_(2) gt H_(2) gt Li_(2)` Solution :The molecular orbital configuration of the given molecules is `H_(2) = sigma2s^(2)` (no electron anti-bonding) `Li_(2)= sigma 1s^(2) sigma ^(* ) 1 s^(2) sigma 2s^(2)` (two anti-bonding electrons) `B_(2)=sigma 1s^(2) 1s^(2) sigma^( ) 1s^(2) sigma 2s^(2) sigma^( *) 2s^(2){pi 2p_(y)^(1)=pi2p_(z)^(1)}` (4 anti-bonding electrons) THOUGH the bond order of all the species are same (B.O = 1) but stability is different. This is DUE to difference in the presence of no. of anti-bonding electron. Higher the no. of anti-bonding electron lower is the stability hence the correct order is `H_(2) gt Li_(2) gt B_(2)`

Discussion

35.	Bond order is a concept in the molecular orbital theory. It depends on the number of electrons in the bonding and antibonding orbitals. Which of the following statements is true about ? The bond order
Answer» Can have a negative quantity Has always an integral VALUE can ASSUME any positive or integral or FRACTIONAL value INCLUDING ZERO Is a non zero quantity Answer :C

Discussion

36.	Bond order for nitrogen molecular is ………………. .
Answer» 1 2 3 0 Solution :3

Discussion

37.	Bond length order in various xenon fluorides is
Answer» `XeF_6gtXeF_4gtXeF_2` `XeF_2=XeF_4=XeF_6` `XeF_2gtXeF_4gtXeF_6` cannot be predicted Answer :C

Discussion

38.	Bond length is maximum in
Answer» HI HBr HCl HF Answer :A

Discussion

39.	Bond length between carbon-carbon in ethylene molecule is
Answer» 1.54 Å 1.35 Å 1.19 Å 2.4 Å Answer :B

Discussion

40.	Bond formed in crystal by anion and cation is
Answer» ionic metallic covalent dipole SOLUTION :GENERALLY cationand anion form ionic BOND.

Discussion

41.	Bond entnalpy of F_(2) is less than of Cl_(2).
Answer» Solution :This is due to relatively LARGE electronic repulsion among the lone pair of `F_(2)` molecule where they are much CLOSER to each other than in CASE of `Cl_(2)`.

Discussion

42.	Bond enthalpy of fluorine is lower than that of chlorine. Why?
Answer» Solution :Fluorine atom being smaller in size, electron-electron repulsions among the lone PAIRS of `F_2` MOLECULE are LARGER compared to that in `Cl_2` molecule.

Discussion

43.	Bond enthalpy of fluorine is lower than that of chlorine why ?
Answer» Solution :BOND enthalpy of `F - F` is smaller DUE to greater REPULSIVE interactions between the lone pair of one F ATOM with those of other. The repulsive interaction arise due to greater concentration of electron density on each F atom because of its extremely SMALL size.

Discussion

44.	Bond enthalpy of bromine is 194 kJ mol^(-). If enthalpy of vapourisation of Br_2 is +30 kJ mol^(-), electron gain enthalpy of Br is -325 kJ mol^(-1) and hydration enthalpy of bromide is -339 kJ mol^(-1) calculate the change in enthalpy for the reaction, 1/2Br_(2)(l) + e^(-) overset(aq)(rarr) Br^(-)(aq).
Answer» Solution :`{:((1)/(2)Br_(2)(l)rarr(1)/(2)Br_(2)(g),,Delta=+15kJmol^(-1)),((1)/(2)Br_(2)(g)rarrBr(g),,DeltaH=+97kJmol^(-1)),(Br(g)rarrBr^(-)(g),,DeltaH=-325kJmol^(-1)),(Br^(-)(g)+AQ rarr Br^(-)(aq),,DeltaH=-339kJ MOL^(-1)):}` Adding these EQUATIONS we get, `(1)/(2)Br_(2)(l)+e^(-)overset(aq)rarrBr^(-)(aq)),DeltaH=-552kJ mol^(-1)`

Discussion

45.	Bond energy of N-N is x kJ "mol"^(-1). Then bond energy of N-=N is
Answer» x kJ `MOL^(-1)` `lt kJ mol^(-1)` 3x kJ `mol^(-1)` `GT 3x kJ mol^(-1)` Answer :B

Discussion

46.	Bond energy of covelent O-H bonds in water is
Answer» GREATER than BOND ENERGY of H-bonds Equal to bond energy of H-bonds Less than bond energy of H-bond NONE of these ANSWER :A

Discussion

47.	Bond energy of a molecule:
Answer» Is always negative Is always POSITIVE Either positive or negative Depends UPON the PHYSICAL STATE of the system Answer :B

Discussion

48.	Bond energy of a molecule
Answer» Is always POSITIVE EITHER positive or NEGATIVE Is always negative Depends UPON the PHYSICAL state of the system Answer :A

Discussion

49.	Bond energy is highest for which of the following?
Answer» `F_2` `Cl_2` `Br_2` `I_2` Solution :Cl-Cl BOND is STRONGEST and hence `Cl_2` has HIGHEST bond ENERGY

Discussion

50.	Bond energy is highest for :
Answer» Sn-Sn Ge-Ge `C-C` `Si-Si` ANSWER :C

Discussion

Explore topic-wise InterviewSolutions in Current Affairs.

Borax on heating with cobalt oxide forms a blue bead of :

Borax is prepared by treating colemanite with :

Borax is ………………. In nature.

Borax is converted into B by the following steps: Boraxoverset(I)toH_(3)BO_(3)overset(Delta)toB_(2)O_(3)overset(II)toB B I and I reagents are

Borax is converted into B by steps Borax overset(1)to H_(3)BO_(3) overset(Delta) to B_(2)O_(3) overset(II)to B I and II reagents are

Borax is a sodium salt of ……………… .

Borax is :

Borax is _____________

Borax heat test is given by

Borax dissolves to give

Borax bead test is responded by :

Borax bead test is not given by :

Borax bead test is given by

Borax bead test depends upon the formation of :

Borax bead is responded generally by :

Borax bead cannot be performed with which of the following salts

Borate from green colour flame when burnt with (Conc. H_2SO_4+ ethanol). Green colour flame is obtained due to due to formation of

Boot polish is what type of colloid.

Books, periodicals, magazines and calendars are printed in large numbers. Type metal used in printing presses as alphabet letter printing contains

Bones glow in the dark. This is due to:

Bones glow in the dark, because:

Bones glow in the dark because

Bone black is a polymorphic form of

Bond type between O and B in BH_3 larr (OC_2H_5)_2 is:

Bond present in O_2 molecule ls

Bond present in benzene diazonium chloride are

Bond order of N_2^- anion is:

Bond order normally gives idea of stability of a molecular species. All the molecules viz. H_(2) Li_(2) and B_(2) have the same bond order yet they are not equally stable. Their stability order is

Bond order is a concept in the molecular orbital theory. It depends on the number of electrons in the bonding and antibonding orbitals. Which of the following statements is true about ? The bond order

Bond order for nitrogen molecular is ………………. .

Bond length order in various xenon fluorides is

Bond length is maximum in

Bond length between carbon-carbon in ethylene molecule is

Bond formed in crystal by anion and cation is

Bond entnalpy of F_(2) is less than of Cl_(2).

Bond enthalpy of fluorine is lower than that of chlorine. Why?

Bond enthalpy of fluorine is lower than that of chlorine why ?

Bond energy of N-N is x kJ "mol"^(-1). Then bond energy of N-=N is

Bond energy of covelent O-H bonds in water is

Bond energy of a molecule:

Bond energy of a molecule

Bond energy is highest for which of the following?

Bond energy is highest for :