52671 + Interview Questions in Chemistry in Class 11

1.	Reaction between acetic acid and ethyl alcohol attains a state of equilibrium in an open vessel but decomposition of CaCO_(3) does not. Why ?
Answer» Solution :Acetic ACID and ethyl alchol are liquids and their products, ethyl and water, are also liquids but one of the products of decomposition of `CaCO_(3)` is gaseous `(CO_(2))`which ESCAPE out and the REVERSE REACTION connot occur.

Discussion

2.	Reaction 2NOCl_((g)) hArr 2NO_((g)) + Cl_(2(g)) at 1060 K temperature K_p is 0.033 "atm"^(-1) . Find K_c.(R=0.082)
Answer» SOLUTION :`3.8xx10^(-4) "MOL L"^(-1)`

Discussion

3.	RCN and RNC are.......... isomers :
Answer» FUNCTIONAL tautomers chain position Solution :R-CN & R-NC functional GROUP is DIFFERENT so functional ISOMERS.

Discussion

4.	RCH=CH_(2)overset(BH_(3)//THF)rarrAoverset(H_(2)O_(2)//OH^(-))rarr B overset (c) rarrRCH_(2)CH_(3) In this sequence of reaction A, B and C are :
Answer» `{:("A","B","C"),((RCH_(2)CH_(2))_(3)",",RCH_(2)CH_(2)OH",",HI):}` `(RCH_(2)CH_(2))B,Runderset(OH)underset("\|")"CH"CH_(3)HI` `(R-underset(CH_(3))underset("\|")"CH"-)B,""Runderset(OH)underset("\|")"CH"CH_(3),HI` None of these Answer :A

Discussion

5.	RbO_(2)is______
Answer» superoxide and PARAMAGNETIC peroxide and diamagnetic superoxide and diamagnetic peroxide and paramagnetic Solution :`RbO_(2)` is a SUPER oxide which contains `Rb^(+)` and `O_(2-)` ions. `O_(2-)` contains one unpaired ELECTRON and hence it is paramagnetic

Discussion

6.	RbO_(2) is……
Answer» superoxideand paramagenetic PEROXIDE and DIAMAGNETIC SUPEROXIDE and diamagnetic peroxide and paramagnetic. Answer :A

Discussion

7.	Rb[ICI_(2)] on heating gives
Answer» `RBCL + ICI` `2Rb + 2Cl_(2) + I_(2)` (from two molecules) `RbI + Cl_(2)` `2Rb[ICI] + Cl_(2)` (from two molecules). SOLUTION :ALKALI metal halides combine with interhalogen compounds forming polyhalides. On heating the reverse reaction occurs. `Rb[ICl_(2)]OVERSET(Delta)rarrRbCl+ICl`

Discussion

8.	Raw material in production of cement is......
Answer» Soil Lime STONE POTASH alum Both (A) and (B) ANSWER :D

Discussion

9.	Rationalize the given statements and give chemical reactions : Lead (IV) chloride is highly unstable towards heat.
Answer» Solution :On moving down group IV, the higher oxidation state becomes UNSTABLE because of the inert pair effect. Pb(IV) is highly unstable and when heated, it reduces to Pb(II). `PbCl_(4(L)) oversetDeltato PbCl_(2(g)) to Cl_(2(g))`

Discussion

10.	Rationalize the given statements and give chemical reactions : Lead (II) chloride reacts with Cl_2 to give PbCl_4.
Answer» Solution : Lead belongs to group 14 of the periodic table. The two oxidation states displayed by this group is +2 and +4. On moving down the group, the +2 oxidation state becomes more stable and the +4 oxidation state becomes LESS stable. This is because of the inert pair effect. Hence, `PbCl_4` is much less stable than `PbCl_2`. HOWEVER, the formation of `PbCl_4` TAKES place when chlorine gas is bubbled through a saturated solution of `PlCl_2`. `PbCl_(2(s)) + Cl_(2(G)) to PbCl_(4(l))`

Discussion

11.	Raw juice in sugar factories is generally concentrated by:
Answer» VACUUM distillation Steam distillation SUBLIMATION crystallization Solution :In SUGAR in dustry, sugar CANE juice is CONCENTRATED by vacuum distillation.

Discussion

12.	Rationalize the given statements and give chemical reactions : Lead is known not to form an iodide, Pbl_4 .
Answer» Solution : LEAD is known not to form Pbl. `Pb^(+4)`is oxidising in NATURE and `I^-` is reducing in nature. A combination of Pb(IV) and iodide ion is not STABLE. Iodide ion is STRONGLY reducing in nature. Pb(IV) oxidises `I^-` to `I_2` and itself gets reduced to Pb(II). `PbI_4to PbI_2 + I_2`

Discussion

13.	Rationalise the statements and give chemical reactions. (iii) Lead is known notto form an iodidePbl_4
Answer» ANSWER :`Pb^(4+)` ION is highly OXIDISING and `I^-` is highly REDUCING in NATURE. So `PbCl_4` does not exist.

Discussion

14.	Rationalise the statements and give chemical reactions. (i) Lead (II) Chloride reacts with Cl_2 to give PbCl_4
Answer» Answer :The +2 STATE is more stable for LEAD (inert PAIR effect) and hence `PbCl_2` will not react with `Cl_2` to FORM relatively less stable `PhCl_4`

Discussion

15.	Rationalise the statements and give chemical reactions. (ii) Lead (IV) chloride is unstable towards heat
Answer» Answer :`PbCl_4` DECOMPOSES on heating to FORM more STABLE `PbCl_2`. So `PbCl_4` is THERMALLY unstable

Discussion

16.	Rationalise the givenstatements and give chemical reaction : (i) lead (II) reacts with Cl_(2) givePbCl_(4) (ii) lead (IV) chloride is highly unstable towards heat (iii) lead is knownnot to form an iodide, PbI_(4)
Answer» Solution :(i) Due to inert pair EFFECT, Pb shows oxidation states of `+2`and `+4`. Since `Cl_(2)` is a STRONG oxidising agent, it oxidises `Pb^(2+)` to `Pb^(4+)` and hence `PbCl_(2)` reacts with `Cl_(2)` to FORM `PbCl_(4)`. `PbCl_(2) (s) + Cl_(2) (g) rarr PbCl_(4)(l)` (ii) Due TOGREATER stability of `+2` over `+4`oxidation state because of inert pair effect , lead (IV) chloride on heating decomposes to give lead (II) chloride and `Cl_(2)`. `PbCl_(4) (l) overset(Delta)rarrPbCl_(2) (s) + Cl_(2) (g)` (iii) Due to oxidising power of `Pb^(4+)` ions and reducingpower of `l^(-)` ion, `PbI_(4)`,does not exist. Alternatively, `Pb-I` bond initially formed during the reactiondoes not releaseenough energy to unpair`6r^(2)` electrons and exciteone of them to the higher`6P`-orbital to have fourunpairedelectronsaround lead atom needed for formationof `PbI_(4)`.

Discussion

17.	Rationalise the given statements and give chemical reactions : • Lead(II) chloride reacts with Cl_(2) to give PbCl_(4). • Lead(IV) chloride is highly unstable towards heat. • Lead is known not to form an iodide, PbI_(4).
Answer» SOLUTION :LEAD(II) CHLORIDE, `PbCl_2` does not react with `Cl_2` to give `PbCl_4`. This is because, DUE to inert-pair effect, the +2 oxidation state of lead is more stable than its +4 oxidation state. In other words, `PbCl_2` is more stable than `PbCl_4`

Discussion

18.	Ratio of the number of waves made by a Bohr electron in one complete revolution in n^(th) orbit and 2^(nd) orbit is 1.5. The value of n is_________
Answer» SOLUTION :`n/2 = 1.5 impliesn=3`

Discussion

19.	Ratio of pi to sigma bonds in benzeneis
Answer» `1 : 4` `1 : 2` `3 : 1` `1 : 6` ANSWER :A

Discussion

20.	Ratio of masses of proton and electron is
Answer» 1.8 `1.8xx10^3` INFINITE `1.8xx10^2` SOLUTION :`(m_p)/(m_e) = (1.67xx10^(-24)G)/(9.1xx10^(-28)g) = 1837`

Discussion

21.	Ratio of fraction of molecules of O_(2) and SO_(2) which lies between U_("rms") to U_("rms")+ du at same temperature is:
Answer» 1 `(1)/SQRT(2)` `(3)/(2sqrt(e))` `(2)/(3e)` ANSWER :B

Discussion

22.	Ratio of hybrid and unhybrid orbitals taking part in bond formation in ethylene molecule
Answer» `1:1` `2:3` `3:4` `1:2` ANSWER :A

Discussion

23.	Ratio K_(p)//K_(c) of the reaction 2 SO_(2) + O_(2)hArr 2 SO_(3)is equal to ……….
Answer» ANSWER :`1//RT`

Discussion

24.	Ratio of average kinetic energies of 28 gm of nitrogen and 16 gm of methaneat room temperature and atmospheric pressureis
Answer» `1 : 1` `7 : 4` `4 : 7` `2 : 5` ANSWER :A

Discussion

25.	Ratio of atoms in an oxide of sulphur is 3:1 .What is the ratio of weight of elements in the oxide?
Answer» ANSWER :`3:1`

Discussion

26.	"Rate of vapourisation is reduced by presence of non-volatile solute "-Explain.
Answer» Solution :When a nonvolatile solute is dissolved in a pure solvent ,the VAPOUR pressure of the pure solvent will decrease .In such solutions , the vapour pressure of the solution will depend only on the solvent molecules as the solute is nonvolatile. For example when sodium chloride is added to the water the vapour pressure of the solution is determined by the number of molecules of the solvent PRESENT in the surface at any time and is proportional to the MOEL fraction of the solvent ` P_("solution ")prop x_A` Where `X_A ` is the mole fraction of the solvent ` P_("solution ")"" =kX_A ` When `X_A"" ="" 1, K =P^(@) _("solvent ") ` ` (P_("solvent ")^(@) ` is the PARTIAL pressure of pure solvent ) ` P_("solution ")""= ""P^(@) _("solvent ") X_A ` `(P_"solution "))/( P_("solvent ")^(@) ) ` ` 1- (P_("solution "))/( P_("solvent ")^(@)) "" ="" 1-X_A ` ` (P_("solvent" )^(@) -P_("solution "))/( P_("solvent ")^(@)) "" =""X_B ` Where `X_B ` is the fraction of the solute ` (therefore X_A +X_B =1, X_B =1-X_A ) ` The above expression gives the relative lowering of vapour pressure.Based on this expression , Raoult''s LAW can also be stated as " the relative lowering of vapour pressure of an ideal solution containing the nonvolatile solute is equal to the mole fraction of the solute at a given temperature ".

Discussion

27.	Rate of the reaction is fastest when Z is
Answer» Cl `OCOCH_(3)` `OC_(2)H_(5)` `NH_(2)` SOLUTION :See relative reactivities of ACID derivatives.

Discussion

28.	Rate of S_(N)1 is maximum when X is
Answer» `X =-OCH_(3)` <BR>`X = -CH_(3)` `X = -NO_(2)` `X = -Br` Answer :A

Discussion

29.	Rate of physisorption increase with
Answer» decrease in TEMPERATURE increase in temperature decrease in pressure decrease in surface AREA. SOLUTION :RATE of PHYSISORPTION increase with decrease in temperature

Discussion

30.	Rate of physical adsorption increases with
Answer» DECREASE in SURFACE area decrease in temperature decrease in pressure increase in temperature Answer :B

Discussion

31.	Rate of melting of ice is equal to __________ .
Answer» rate of freezing of ICE rate of melting of ice rate of freezing WATER rate of melting of water Answer :C

Discussion

32.	'Rate of Melting = Rate of freezing'' When is the above condition achieved ? Explain with an example.
Answer» Solution :Let US consider the melting of ICE in a closed container at 273 K. In the PROCESS the total number of WATER molecules leaving from and returning to the solid phase at any instant are equal. If some ice-cubes and water are placed in a thermos flask (at 273 K and 1 at, pressure). then there will be no change in the mass of ice and water. At equilibrium, `{:("Rate of meltingRate of FREEZING"),("="),("of iceof water"),(""H_(2)O(S)hArrH_(2)O(l)):}` The temperature at which the solid and liquid phases of a substance are at equilibrium is called the melting point or freezing point of that substance.

Discussion

33.	Rate of evaporisation increases with increase in 3 surface area, but not vapour pressure. Why?
Answer» Solution :As the surface area INCREASES, more number of molecules will escape per unit time. Therefore, rate of evaporation increases. But vapour PRESSURE in nothing but pressure and is DEFINED as FORCE per unit area.

Discussion

34.	Rate of diffustion of a gas is :
Answer» directly PROPORTIONAL to its density directly proportional to its molecular mass directly proportional to the square ROOT of its MOLAR mass inversely propertional to the squaure root of its molar mass. Solution :is the CORRECT answer.

Discussion

35.	Rate of diffusion of 1 mole CO and 2 mole N_(2) in a container are same Rate of diffusion prop sqrt(1//M) at constant P,T .
Answer» <P> Solution :`r PROP (P)/(SQRT(M))` at CONSTANT `T` .

Discussion

36.	Rate of diffusion of ozonised oxygen is 0.4 sqrt(5)times that of pure oxygen. What is the percent degree of association of oxygen assuming pure O_(2) in the sample initially ?
Answer» 20 40 60 30 Solution :`3O_(2) harr 2O_(3(g))` `(r_("mix"))/(rO_(2))=sqrt((32)/(M_("mix")))=0.4sqrt5 IMPLIES M_("mix")=40g // "MOLE"`

Discussion

37.	Rate of diffusion ofa gas is
Answer» directly PROPORTIONAL to its density directly proportional to its MOLECULAR weight directly proportional to its SQUARE ROOT of its molecular weight INVERSELY proportional to the square root of its molecular weight Answer :A::C::D

Discussion

38.	Rate of Bimolecular elimination (E2) reaction for the following :
Answer» Same for both conformers I gt II ii gt I Can't SAY anything about rate of E-2 reaction Solution :The more stable CONFORMATION of chlorocyclohexane does not UNDERGO an E-2 elimination easily while the less stable conformer , with the chloro group in the AXIAL position , readily undergoes an E-2 reaction.

Discussion

39.	Rare gases are sparingly soluble in water because of
Answer» hydrogen BONDING dipole-dipole intrarction INDUCED dipole-induced dipole INTERACTION dipole-induced dipole interaction ANSWER :D

Discussion

40.	Rare earths are generally
Answer» Actinides f-block ELEMENTS INNER TRANSITION elements Lanthanides Answer :D

Discussion

41.	Rank the following free radicals in order of decreasing stability (I)C_(6)H_(5)CH_(6)H_(5)(II) C_(6)H_(5) -CH-CH=CH_(2)(III) CH_(3)-overset(.)CH - CH_(3)(IV) C_(6)H_(5)-overset(.)CH-CH_(3)(V) CH_(3)CH=CHCH_(2)overset(.)CH_(2)(VI) CH_(3)-CH_(2)-underset(CH_(3)) underset(\|)overset(.)C-CH_(3)
Answer» `I gt II gt IV gt CI gt HI gt V ` `VI gt V gt IV gt III gt II gt I` `I gt II gt III gt IV gt V gt VI` `I gt IV gt VI gt V gt II gt III` Answer :A

Discussion

42.	Rank the following in the order of increasing entropy : (a) 1 mole of H_(2)O(l) at 25^(@)C and 1 atm. Pressure. (b) 2 moleof H_(2)O(s) at 0^(@)C and 1 atm. Pressure. (c )1 moleof H_(2) O(v) at 100^(@)C and 1 atm. Pressure. (d) 1 moleof H_(2)O(l)at 0^(@)C and 1 atm. pressure.
Answer» SOLUTION :(b)`LT (d) lt (a) lt (C )`. This is because solid is LESS RANDOM than liquid which is tun is less random than gas .For the same state, at the same pressure, higher the temperature , greater is the randomness.

Discussion

43.	Rank the following compounds in order of decreasing reactivity towards electrophilic substitutionreaction I) ChlorobenzeneII) 4-Nitrochlorobenzene III) 2,4-dinitrochlorobenzene IV) 2,4,6-trinitrochlorobenzene
Answer» `I gt II gt III gt IV` `I gt III gt II gt IV` `III gt I gt IV gt II` `IV gt III gt II gt I` Solution :Increase and presence ofewg at o/p positions deactivates the BENZENE RING TOWARDS ARES

Discussion

44.	Rank the following carbocations in order of increasing stability :
Answer» Solution :STRUCTURE A is a primary carbocation, B is tertiary and C is secondary.Therefore, in ORDER of increasing stability, `A LT C lt B`.

Discussion

45.	Rank the following alkyl bromides in order of decreasing reactivity (from fastest to slowest) as a substrate in an S_(N)2 reaction.
Answer» Solution :We examine the CARBON bearing the leaving group in each instance to ASSESS the steric hindrance to an `S_(n)2`reaction at that carbon. In C it is `3^(@)`, therefore, three groups would HINDER the approach of a nucleophile, so this alkyl bromide would react most slowly. In the carbon bearing the leaving group is `2^(@)` (two groups hinder the approach of the nucleophile), while in both A and B it is `1^(@)` (one group hin ders the nucleophile.s approach). Therefore, D would react faster than C, but slower than either A or B. But, what about A and B? They are both `1^(@)`alkyl bromides, but B has a methyl group on the carbon adjacent to the one bearing the bromine, which would provide steric hindrance to the approaching nucleophile that would not be present in A. The order of reactivity, therefore, is `A gt B gt Dgt gt C`.

Discussion

46.	Rank in order of increasing rate of reaction towards EAS with bromine in the presence of FeBr_(3)
Answer» BltAltC BltCltA AltBltC AltCltB Solution :EDG INCREASE REACTIVITY and EWG DECREASE reactivity towards EAS.

Discussion

47.	Range the following free radicals in increasing order of their stability and give appropriate reasons.
Answer» Answer :Stability ORDER `I lt II lt III lt IV` IV is most stable being `3^(º)` and delocalised.

Discussion

48.	When a system is in equilibrium state
Answer» GAS LIQUID SOLUTION SOLID ANSWER :A

Discussion

49.	Random motion of colloid particle is known as
Answer» Dialysis Brownian movement Electro-osmosis Tyndall effect Answer :B

Discussion

50.	Ram joined Kota test series, where he was asked to calculates DeltaS_(sys) for a process as described below. A diathermic container (containing an ideal gas) fitted with a piston at equilibrium (without any topper) and has initial volume 600 liter. Now the external pressure is suddenly reduced to 1 bar and allowed the piston to move upward isothermally. In this process, system absorb 600 kJ heat. He calculated DeltaS _(sys) =2kJ//K but was awarded zero marks. To identify his mistake he contacted his Kota feiend Shyam and explained his problem.When shyam asked how Ram calculated DeltaS_(sys,) Ram said simple !by q//T. If you are Shyam, then help Ram in getting crrect answer (in kJ//K). [In 11=2.4]
Answer» ANSWER :5

Discussion

Explore topic-wise InterviewSolutions in Current Affairs.

Reaction between acetic acid and ethyl alcohol attains a state of equilibrium in an open vessel but decomposition of CaCO_(3) does not. Why ?

Reaction 2NOCl_((g)) hArr 2NO_((g)) + Cl_(2(g)) at 1060 K temperature K_p is 0.033 "atm"^(-1) . Find K_c.(R=0.082)

RCN and RNC are.......... isomers :

RCH=CH_(2)overset(BH_(3)//THF)rarrAoverset(H_(2)O_(2)//OH^(-))rarr B overset (c) rarrRCH_(2)CH_(3) In this sequence of reaction A, B and C are :

RbO_(2)is______

RbO_(2) is……

Rb[ICI_(2)] on heating gives

Raw material in production of cement is......

Rationalize the given statements and give chemical reactions : Lead (IV) chloride is highly unstable towards heat.

Rationalize the given statements and give chemical reactions : Lead (II) chloride reacts with Cl_2 to give PbCl_4.

Raw juice in sugar factories is generally concentrated by:

Rationalize the given statements and give chemical reactions : Lead is known not to form an iodide, Pbl_4 .

Rationalise the statements and give chemical reactions. (iii) Lead is known notto form an iodidePbl_4

Rationalise the statements and give chemical reactions. (i) Lead (II) Chloride reacts with Cl_2 to give PbCl_4

Rationalise the statements and give chemical reactions. (ii) Lead (IV) chloride is unstable towards heat

Rationalise the givenstatements and give chemical reaction : (i) lead (II) reacts with Cl_(2) givePbCl_(4) (ii) lead (IV) chloride is highly unstable towards heat (iii) lead is knownnot to form an iodide, PbI_(4)

Rationalise the given statements and give chemical reactions : • Lead(II) chloride reacts with Cl_(2) to give PbCl_(4). • Lead(IV) chloride is highly unstable towards heat. • Lead is known not to form an iodide, PbI_(4).

Ratio of the number of waves made by a Bohr electron in one complete revolution in n^(th) orbit and 2^(nd) orbit is 1.5. The value of n is_________

Ratio of pi to sigma bonds in benzeneis

Ratio of masses of proton and electron is

Ratio of fraction of molecules of O_(2) and SO_(2) which lies between U_("rms") to U_("rms")+ du at same temperature is:

Ratio of hybrid and unhybrid orbitals taking part in bond formation in ethylene molecule

Ratio K_(p)//K_(c) of the reaction 2 SO_(2) + O_(2)hArr 2 SO_(3)is equal to ……….

Ratio of average kinetic energies of 28 gm of nitrogen and 16 gm of methaneat room temperature and atmospheric pressureis

Ratio of atoms in an oxide of sulphur is 3:1 .What is the ratio of weight of elements in the oxide?

"Rate of vapourisation is reduced by presence of non-volatile solute "-Explain.

Rate of the reaction is fastest when Z is

Rate of S_(N)1 is maximum when X is

Rate of physisorption increase with

Rate of physical adsorption increases with

Rate of melting of ice is equal to __________ .

'Rate of Melting = Rate of freezing'' When is the above condition achieved ? Explain with an example.

Rate of evaporisation increases with increase in 3 surface area, but not vapour pressure. Why?

Rate of diffustion of a gas is :

Rate of diffusion of 1 mole CO and 2 mole N_(2) in a container are same Rate of diffusion prop sqrt(1//M) at constant P,T .

Rate of diffusion of ozonised oxygen is 0.4 sqrt(5)times that of pure oxygen. What is the percent degree of association of oxygen assuming pure O_(2) in the sample initially ?

Rate of diffusion ofa gas is

Rate of Bimolecular elimination (E2) reaction for the following :

Rare gases are sparingly soluble in water because of

Rare earths are generally

Rank the following free radicals in order of decreasing stability (I)C_(6)H_(5)CH_(6)H_(5)(II) C_(6)H_(5) -CH-CH=CH_(2)(III) CH_(3)-overset(.)CH - CH_(3)(IV) C_(6)H_(5)-overset(.)CH-CH_(3)(V) CH_(3)CH=CHCH_(2)overset(.)CH_(2)(VI) CH_(3)-CH_(2)-underset(CH_(3)) underset(|)overset(.)C-CH_(3)

Rank the following in the order of increasing entropy : (a) 1 mole of H_(2)O(l) at 25^(@)C and 1 atm. Pressure. (b) 2 moleof H_(2)O(s) at 0^(@)C and 1 atm. Pressure. (c )1 moleof H_(2) O(v) at 100^(@)C and 1 atm. Pressure. (d) 1 moleof H_(2)O(l)at 0^(@)C and 1 atm. pressure.

Rank the following compounds in order of decreasing reactivity towards electrophilic substitutionreaction I) ChlorobenzeneII) 4-Nitrochlorobenzene III) 2,4-dinitrochlorobenzene IV) 2,4,6-trinitrochlorobenzene

Rank the following carbocations in order of increasing stability :

Rank the following alkyl bromides in order of decreasing reactivity (from fastest to slowest) as a substrate in an S_(N)2 reaction.

Rank in order of increasing rate of reaction towards EAS with bromine in the presence of FeBr_(3)

Range the following free radicals in increasing order of their stability and give appropriate reasons.

When a system is in equilibrium state

Random motion of colloid particle is known as