94420 + Interview Questions in Chemistry in Class 12

1.	At S.T.P. 1gCaCO_(3) on decomposition gives CO_(2)
Answer» 22.4 litres 2.24 litres 0.224 litre 11.2 litres Solution :`underset((40+12+16x3)=100gm)(CaCo_(3))rarr CAO +underset(22.4 "litre")(CO_(2))uarr` `:'`At S.T.P. 100G `CaCO_(3)` PRODUCE `=22.4 ` litre of `CO_(2)` `:. `At S.T.P. 1g `CaCO_(3)` produce`=(22.4)/(100)=.224` litre of `CO_(2)`

Discussion

2.	At STP 1.12 litre of H_(2) is obtained on flowing a current for 965 seconds in a solution . The value of current is
Answer» 10 1 1.5 2 Solution :`2H^(+)+underset(2"mole"2xx96500C)(2E^(-))rarrunderset("1mole"22.4"lt")(H_(2)` To liberate 22.5 lt of `H_(2)` GAS, electricity REQUIRED `=2xx96500C` To liberate 1.12 lt of `H_(2)` gas, electricity required `=(2xx96500xx1.12)/(965"sec")=10` ampere

Discussion

3.	At STP 10 L of H_(2)S was reacted with 10 Lof SO_(2). The volume of gas remaining after the reaction is complete would be
Answer» 5 L 10 L 15 L 20 L SOLUTION :N/A

Discussion

4.	At STP, 0.50 mol H_(2) gas and 1.0 mol He gas
Answer» Have equal AVERAGE KINETIC ENERGIES Have equal molecular speeds Occupy equal volumes Have equal EFFUSION rates Solution :For same TEMPERATURE kinetic energies of `H_(2)` & He molecule will be same because kinetic energy depends only on temperature.

Discussion

5.	At STP 1.12 litre of H_(2) is obtained on flowing a current for 965 seconds in a solution. The value of current in amperes is
Answer» 10 `1.0` `1.5` `2.0` Solution :`1.12 L H_(2) = 0.1 g eq. of H_(2)` Q = 0.1 F = 9650 C . HENCE , `I = (Q)/(t) = (9650)/(965) = 10 A` .

Discussion

6.	At S.T.P. 0.50mol of H_(2) gas and 1.-0 mol of He gas
Answer» have EQUAL KINETIC energies have equal MOLECULAR speeds occupy equal volumes have equal EFFUSION rates. Answer :A

Discussion

7.	At starting 20 moles of H_2,8 moles of I_2 was taken in a 10 litre flask and at equilibrium the density of HI was found to be 0.0384 g mL^(-1) . What will be the degree of dissociation for HI keeping the temperature and pressure constant ,
Answer» 0.45 0.88 0.32 0.25 Answer :B

Discussion

8.	At same temperature and pressure, the rate of diffusion of hydrogen gas is 3 sqrt( 3) times that of a hydrocarbon having molecular formula, C_(n) H_(2n-2).The value of n is
Answer» 3 2 6 4 Solution :`( r ( H_(2)))/( "r ( HYDROCARBON)") = sqrt(("M(hydrocarbon)")/(M(H_(2))))` `3 sqrt( 3) = sqrt(("M(hydrocarbon)")/(2))` M ( hydrocarbon) = `(3sqrt( 3))^(2) xx 2 = 54 ` For `C_(N)H_(2n-2) .12N+(2n-2) = 54` or n = 4

Discussion

9.	At room temperaturee, for the reaction NH_(4)SH_((s))hArrNH_(3(s))+H_(2)S_((g))
Answer» <P>`K_(p)=K_(c)` `K_(p)gtK_(c)` `K_(p)ltK_(c)` `K_(p)and K_(c)` do not RELATE ANSWER :B

Discussion

10.	At room temperature which of the following will respond Lucas test ?
Answer» Butanol Propanol 2-methyl propane-2-ol None of these Solution :2-methyl propane-2-ol

Discussion

11.	At room temperature, the reaction between NO and O_2 to give NO_2 is the fast, while that between CO and O_2is slow. It is due to:
Answer» CO is smaller in size than that of NO CO is poisonous The activation energy for the reaction, `2NO+O_2rarr2NO_2`is less then `2CO+O_2rarr2CO_2` NONE of these Answer :C

Discussion

12.	At room temperature, the reaction between NO and O_(2) to give NO_(2) is fast, while that between CO and O_(2) is slow. It is due to:
Answer» CO is smaller in SIZE that of NO CO is POISONOUS the ACTIVATION energy for the reaction, `2NO+O_(2)rarr 2NO_(2)` is less than `2CO+O_(2)rarr 2CO_(2)` none of the above Answer :C

Discussion

13.	At room temperature, the reaciton betweeen water and fluorine produces
Answer» HF and `H_(2)O_(2)` `HF, O_(2)` and `F_(2)O_(3)` `F^(-), O_(2)` and `H^(+)` HOF and HF SOLUTION :`{:(H_(2)O_((l))+F_(2(g))rarrHF_((AQ))+O_(2)),(""DARR),(""H_((aq))^(+)+F_((aq))^(-)):}`

Discussion

14.	At room temperature the following reactions proceed nearly to completion:2NO + O_2 to 2NO_2 to N_2O_4The dimer, N_2O_4solidifies at 262 K. A 250-ml flask and a 100-ml flask are separated by a stopcock. At 300 K the nitric oxide in the larger flask exerts a pressure of 1.053 atm and the smaller one contains oxygen at 0.789 atm. The gases are mixed by opening the stopcock and after the end of the reaction the flasks are cooled to 220 K. Neglecting the vapour pressure of the dimer, find out the pressure and composition of the gas remaining at 220 K. Assume the gases to behave ideally.
Answer» SOLUTION :0.221 ATM, NO- 0.0043 MOL

Discussion

15.	At room temperature the eclipsed and the staggered forms of ethane cannot be isolated because
Answer» both the conformers are equally stable They interconvert rapidly there is a large ENERGY BARRIER of rotation about the `sigma ` BOND the energy difference between the conformers is large Answer :B

Discussion

16.	At room temperature, the eclipsed and staggered forms of ethane can not be isolated because
Answer» Theyinterconvert rapidly Both the conformers are equally stable The ENERGY difference between the conformers is large There is a large energy barrier of rotation about the `sigma` bond Solution :In STAGGERED and eclipsed conformation of ethane, the basic structure of the ethane molecule and its various bond angles and bond lengths remain same. Since the repulsion between the non-bonded HYDROGEN atoms on the two carbons are minimum in the staggered conformation, hence staggered conformation is more stable than the eclipsed conformation by about `12.55 kJ mol^(-1)`. Further since this energy barrier of `12.55 kJ mol^(-1)` is very small and can be easily MET by the collisions of the molecules at room TEMPERATURE, hence these two conformation of ethane are readily interconvertible and hence cannot be separated at room temperature.

Discussion

17.	At room temperature solid paraffin is
Answer» `C_3H_8` `C_8H_18` `C_4H_10` `C_20H_42` ANSWER :D

Discussion

18.	At room temperature, sodium crystallises in a body centred cubic cell with a = 4.24 Å.The theoretical density of sodium is –( Atomic mass of sodium = 23.0 g mol^(–1)) (A) 2.05 g cm^(–3) (B) 3.45 g cm^(–3) (C) 1.00 g cm^(–3) (D) 3.55 g cm^(–3)
Answer» Solution : (C ) The value of Z for a bcc unit cell is 2. VOLUMEV= `(4.24 A)^(3) THEREFORE =(ZM)/(NV)=(2xx23)/((6.023xx10^(23))xx(4.24xx10^(-8))^(3)` =1.00 `g//cm^(3)`

Discussion

19.	At room temperature ,sodium crystallizes in a body centred cubic lattice with a =4.24overset@A.The theoretical density of sodium (At.wt.of Na=23)is:
Answer» `1.002gcm^-3` `2.002gcm^-3` `3.002gcm^-3` NONE of these Answer :A

Discussion

20.	At room temperature, NH_(3) gas at 1 atm and HCl gas at P atm are allowed to effuse through identical pinholes from oppoite ends of a glass tube of 1 metre length and uniform cross section. NH_(4)Cl is first fomed at a distance of 60 cm from the end through whieh, HCI gas is sent in. What is the value of P?
Answer» SOLUTION :2.198 ATM

Discussion

21.	At room temperature, hydrogen halides are gases but ……………..can be readily liquefied.
Answer» SOLUTION :HYDROGEN FLUROIDE

Discussion

22.	At room temperature formaldehyde is :
Answer» GAS LIQUID Solid None Answer :A

Discussion

23.	At room temperature formaldehyde is
Answer» GAS LIQUID SOLID NONE of these ANSWER :A

Discussion

24.	At room temp.,formaldehyde is a _____.
Answer» GAS LIQUID Solid None Answer :A

Discussion

25.	At room temperature following reaction goes to cormpletion 2NO+O_(2) rarr 2NO_(2)rarr N_(2)O_(4) Dimer N_(2)O_(2)" at "262 K is solid. A 250 ml flask and a 100 ml flask are separated by a stop cock. At 300 K, the nitric oxide in the larger flask exerts a pressure of 1.053 atm and the smaller one contains O_(2)" at "0.789 atm. The gases are mixed by opening the stop cock and after the. end of the reaction, the flasks are cooled to 220 K. Neglecting the vapour pressure of dimer find out the pressure and composition of gas remaining at 220 K. (Assume gases behave ideàlly).
Answer» SOLUTION :0.221 ATM

Discussion

26.	At room temperature, formaldehyde changed to
Answer» paraldehyde hexose trioxane which does reduce Tollen's reagent NONE of the above SOLUTION :FORMALDEHYDE changed to trioxane which does not reduce Tollen's reagent.

Discussion

27.	At room temperature F_(2)reacts with all non metals except
Answer» B and C S and `Br_(2)` `O_(2)`and `N_(2)` `H_(2) ` and TE ANSWER :C

Discussion

28.	At room temperature F_2 and Cl_2 are gases Br_2 is a liquid and I_2 is solid. This is because
Answer» Dipole-induced dipole interaction increases with molecular SIZE Dipole-dipole INTERACTIONS increases with molecular size Dispersion (London) interaction increases with molecular size Dispersion ( London) interactions DECREASES with molecular size and POLARITY increases with molecular size Answer :C

Discussion

29.	At room temperature ammonia gas at 1 atm pressure and hydrogen chloride at p atmospheric pressure are allowed to diffuse through identical pin holes from opposite ends of a glass tube of 1 metre length and of uniform cross-section. Ammonium chloride is first formed at a distance of 60 cm from the end through which HCl gas is sent in. what is the value of p ?
Answer» <P> Solution :In this problem the pressure under which the two gases are DIFFUSING are different. `(r_(NH_(3)))/(r_(HCl)) = sqrt((M_(HCl))/(M_(NH_(3)))) xx (p_(NH_(3)))/(p_(HCl)) = (40)/(60)` or `sqrt((36.5)/(17)) xx (1)/(p_(HCl)) = (40)/(60)` `p_(HCl) = 2.198` atm.

Discussion

30.	At room temperature, all the elements of group 17 exist in the gaseous state.
Answer» Solution :At room TEMPERATURE, only `F_2` and `Cl_2`, of GROUP 17 EXIST in the gaseous STATE.

Discussion

31.	At relatively high pressure, van der Waal's equation for one mole of gas reduces to
Answer» PV = RT PV = RT + a/V PV = RT + PB `PV = RT - (a/ V^2)` ANSWER :C

Discussion

32.	At room tempearture and pressure, two flasks of equal volumes are filled with H_(2) and SO_(2) separately. Particles which are equal in number, in the two flasks are:
Answer» ATOMS ELECTRONS molecules NEUTRONS ANSWER :C

Discussion

33.	At red heat KMnO_(4) decompose into,
Answer» `K_(2)MnO_(2)` `K_(2) MnO_(3)` `K_(2)SO_(4)` `KHSO_(4)` ANSWER :B

Discussion

34.	At present the main source of energy that is driving our economy is fossil fuel.
Answer» ANSWER :1

Discussion

35.	At pH = 4, glycine exists as
Answer» `H_(3)overset(+)(N)-CH_(2)-COO^(-)` `H_(3)overset(+)(N)-CH_(2)-COOH` `H_(2)N-CH_(2)-COOH` `H_(2)N-CH_(2)-COO^(-)` SOLUTION :At pH = 4 (i.e. acidic MEDIUM), an amphoteric Zqitter ion structure CHANGES into cation when an ACID is added to it. `underset(""^(o+)NH_(3))underset("\|")(R )-CH-COO^(Ө)+H^(+)rarr underset(""^(o+)NH_(3))underset("\|")(R )-CH-COOH`

Discussion

36.	At pH=4,CrO_(4)^(2-) exists as
Answer» `CrO_(4)^(2-)` `CrO_(3)` `CrO_(2)^(2-)` `Cr_(2)O_(7)^(2-)` Solution :PH=4 MEANS acidic medium `2CrO_(4)^(2-)+2H^(+)rarrCr_(2)O_(7)^(2-)+H_(2)O (CrO_(4)^(2-)UNDERSET(pHgt7)overset(PHLT7)hArrCr_(2)O_(7)^(2-))`

Discussion

37.	At pH 4 , glycine exists as
Answer» `H_(3)overset(N)-CH_(2)COO^(-)` `H_(3)overset(N)-CH_(2)COOH` `H_(2)NCH_(2)COOH` `H_2NCH_(2)COO^(-)` ANSWER :B

Discussion

38.	At pH = 4, glycine exists as …………………..
Answer» CATION ANION ZWITTER ION NEUTRAL molecule Solution :Cation

Discussion

39.	(At pH =2) glycine exists as
Answer» `H_(3)N^(+) -CH_(2)-COO^(-)` `H_(3)N^(+)-CH_(2)-COOH` `H_(2)N-CH_(2)-COOH` `H_(2)N-CH_(2)-COO^(-)` ANSWER :B

Discussion

40.	At pH =4. Cr_(2)O_(7)^(2-) existas
Answer» `CrO_(2)^(2+)` `CrO_(4)^(2-)` `CrO_(4)^(2+)` `Cr_(2)O_(7)^(2-)` Answer :D

Discussion

41.	At particular concentration, the half life of the reaction is 100 minutes. When the concentration of reactantbecomes double half life becomes 25 minutes, then what will be the order of the reaction ?
Answer» 1 2 0 3 Answer :D

Discussion

42.	At ordinary temperature Cl_2 reacts with
Answer» `O_(2)` `N_(2)` He Cu Answer :D

Discussion

43.	At ordinary temperature and pressure, amonh halogens, chlorine is a gas, bromine is a liquid and iodine is solid. This is because:
Answer» ANSWER :B

Discussion

44.	At ordinary temperature and pressure, among halogens, chlorine is gas, bromine is a liquid, and iodine is a solid, because
Answer» The order of stabiity `= I_(2) gt Br_(2) gt Cl_(2)` The order of DENSITY `= I_(2) gt Br_(2) gt Cl_(2)` The order of specific heat `= Cl_(2) gt Br_(2) gt I_(2)` The order of intermolecular forces `= Cl_(2) lt Br_(2) lt I_(2)` Solution :Density `prop` Mass thus `I_(2) gt Br_(2) gtCl_(2)` (C ) BOND energydecreases thus specific heat (or) amount at NEAR required decreases down the group `Cl_(2) gt Br_(2) gt I_(2)` , order of intermolcular force `I_(2) gt Br_(2) gt Cl_(2)`

Discussion

45.	At ordinary temperature and pressure, among halogens, chlorine is a gas, bromine is a liquid and jodine is a solid. Why?
Answer» Solution :INTERMOLECULAR FORCES among molecules of chlorine are the weakest and those in iodine are the STRONGEST.

Discussion

46.	At N.T.P. the volume of a gas is found to be 273 ml. What will be the volume of this gas at 600 mm Hg and 273^(@)C
Answer» 391.8 ml 380 ml 691.6 ml 750 ml Solution :`V_(2)=(P_(1)V_(1))/(T_(1))(T_(2))/(P_(2))=(760)/(600)XX(546)/(273)xx273=691.6 ml`

Discussion

47.	At NTP, 5.6 litre of a gas weight 8 g. The vapour density of the gas is :
Answer» 32 40 16 8 Answer :C

Discussion

48.	At NTP, 10 litre of hydrogen sulphide gas reacted with 10 litre of sulphur dioxide gas. The volume of gas, after the reaction is complete, would be:
Answer» 5litre 10litre 15litre 20litre Answer :A

Discussion

49.	At normal temperature the barometric pressure is 76 cm, then the height of water column if water is used instead of mercury is (Give: density of mercury and water at the same temperature is 13.6 g/cc and 0.999 g/cc)
Answer» 1034.6 cm 9230.2cm 10346 .08 cm 103.46 cm Solution :The barometer contains mercury, so the pressure =DGH As the presure is CONSTANT, so we can write the equation `d_(1)gh_(1)=d_(2)gh_(2)` where `d_(1)=` density of mercury `=13.6` g/cc `h_(1)=` height of mercury column =76 cm `d_(2)=` density of water =0.999g/cc `h_(2)=` height of water column =? g=acceleration due to GRAVITY `implies76xx13.6=h_(2)xx0.999` `impliesh_(2)=(76xx13.6)/0.999=1034.6cm`

Discussion

50.	At normal temperature iodoform is
Answer» THICK VISCOUS liquid Gas Volatile liquid SOLID Solution :At ROOM temperature iodoform is the yellow solid.

Discussion

Explore topic-wise InterviewSolutions in Current Affairs.

At S.T.P. 1gCaCO_(3) on decomposition gives CO_(2)

At STP 1.12 litre of H_(2) is obtained on flowing a current for 965 seconds in a solution . The value of current is

At STP 10 L of H_(2)S was reacted with 10 Lof SO_(2). The volume of gas remaining after the reaction is complete would be

At STP, 0.50 mol H_(2) gas and 1.0 mol He gas

At STP 1.12 litre of H_(2) is obtained on flowing a current for 965 seconds in a solution. The value of current in amperes is

At S.T.P. 0.50mol of H_(2) gas and 1.-0 mol of He gas

At starting 20 moles of H_2,8 moles of I_2 was taken in a 10 litre flask and at equilibrium the density of HI was found to be 0.0384 g mL^(-1) . What will be the degree of dissociation for HI keeping the temperature and pressure constant ,

At same temperature and pressure, the rate of diffusion of hydrogen gas is 3 sqrt( 3) times that of a hydrocarbon having molecular formula, C_(n) H_(2n-2).The value of n is

At room temperaturee, for the reaction NH_(4)SH_((s))hArrNH_(3(s))+H_(2)S_((g))

At room temperature which of the following will respond Lucas test ?

At room temperature, the reaction between NO and O_2 to give NO_2 is the fast, while that between CO and O_2is slow. It is due to:

At room temperature, the reaction between NO and O_(2) to give NO_(2) is fast, while that between CO and O_(2) is slow. It is due to:

At room temperature, the reaciton betweeen water and fluorine produces

At room temperature the eclipsed and the staggered forms of ethane cannot be isolated because

At room temperature, the eclipsed and staggered forms of ethane can not be isolated because

At room temperature solid paraffin is

At room temperature, sodium crystallises in a body centred cubic cell with a = 4.24 Å.The theoretical density of sodium is –( Atomic mass of sodium = 23.0 g mol^(–1)) (A) 2.05 g cm^(–3) (B) 3.45 g cm^(–3) (C) 1.00 g cm^(–3) (D) 3.55 g cm^(–3)

At room temperature ,sodium crystallizes in a body centred cubic lattice with a =4.24overset@A.The theoretical density of sodium (At.wt.of Na=23)is:

At room temperature, hydrogen halides are gases but ……………..can be readily liquefied.

At room temperature formaldehyde is :

At room temperature formaldehyde is

At room temp.,formaldehyde is a _____.

At room temperature, formaldehyde changed to

At room temperature F_(2)reacts with all non metals except

At room temperature F_2 and Cl_2 are gases Br_2 is a liquid and I_2 is solid. This is because

At room temperature, all the elements of group 17 exist in the gaseous state.

At relatively high pressure, van der Waal's equation for one mole of gas reduces to

At room tempearture and pressure, two flasks of equal volumes are filled with H_(2) and SO_(2) separately. Particles which are equal in number, in the two flasks are:

At red heat KMnO_(4) decompose into,

At present the main source of energy that is driving our economy is fossil fuel.

At pH = 4, glycine exists as

At pH=4,CrO_(4)^(2-) exists as

At pH 4 , glycine exists as

At pH = 4, glycine exists as …………………..

(At pH =2) glycine exists as

At pH =4. Cr_(2)O_(7)^(2-) existas

At particular concentration, the half life of the reaction is 100 minutes. When the concentration of reactantbecomes double half life becomes 25 minutes, then what will be the order of the reaction ?

At ordinary temperature Cl_2 reacts with

At ordinary temperature and pressure, amonh halogens, chlorine is a gas, bromine is a liquid and iodine is solid. This is because:

At ordinary temperature and pressure, among halogens, chlorine is gas, bromine is a liquid, and iodine is a solid, because

At ordinary temperature and pressure, among halogens, chlorine is a gas, bromine is a liquid and jodine is a solid. Why?

At N.T.P. the volume of a gas is found to be 273 ml. What will be the volume of this gas at 600 mm Hg and 273^(@)C

At NTP, 5.6 litre of a gas weight 8 g. The vapour density of the gas is :

At NTP, 10 litre of hydrogen sulphide gas reacted with 10 litre of sulphur dioxide gas. The volume of gas, after the reaction is complete, would be:

At normal temperature the barometric pressure is 76 cm, then the height of water column if water is used instead of mercury is (Give: density of mercury and water at the same temperature is 13.6 g/cc and 0.999 g/cc)

At normal temperature iodoform is