94420 + Interview Questions in Chemistry in Class 12

1.	HeLa cells used in cell biology are
Answer» CANCEROUS CELLS grown in cancer research laboratory Cervical cancer CELL derivatives Both (a) and (b) None of these Answer :C

Discussion

2.	Helium and neon do not form compounds with fluorine. Why ?
Answer» SOLUTION :He and Ne do not contain d-orbitals in their RESPECTIVE valence shells and HENCE their electrons cannot be PROMOTED to higher energy levels LIKE that in Xe to form bonds. Therefore, He and Ne do not form compounds with fluorine.

Discussion

3.	Hardness of transition elements is due to :
Answer» Large atomic size Metallic BONDING Covalent bonds high ionisation energy Answer :C

Discussion

4.	Heisenberg's uncertainty principle cannot be applied to stationary electron. Why?
Answer» Solution :(HINT : VELOCITY of stationary electron is zero)

Discussion

5.	Heisenberg uncertainty principle precludes the simultaneous measurement of
Answer» ENERGY and VELOCITY RADIUS and CHARGE density Position and momentum Probability and intensity. Answer :C

Discussion

6.	Heavy water posseses:
Answer» Insoluble impurities like silica Impurities like carbonates and BICARBONATES of calcium and magnesium High DENSITY and different physical properties than those of water The CAPACITY to expedite the RATE ofnuclear reactions Answer :C

Discussion

7.	Hardest s-block metal is-
Answer» `LI` `NA` `MG` `Be` ANSWER :D

Discussion

8.	Hardest element of group 13 is:
Answer» B Ga Al In Answer :A

Discussion

9.	Hardening of oils is caused by
Answer» `H_(2)` `N_2` `O_2` `CO_2` SOLUTION :Oil (UNSATURATED) `+H_(2) overset(NI)to` Fat (saturated)

Discussion

10.	Hardening of leather in tanning industry is based on
Answer» ELECTROPHORESIS Electro-osmosis Mutual coagulation Tyndall EFFECT SOLUTION :Mutual coagulation

Discussion

11.	Hard water when passed through ion exchange resin containing RCOOH group, becomes free from
Answer» `CL^(-)` `SO_(4)^(2-)` `H_(3)O^(+)` `Ca^(+2)` SOLUTION :`RCOOH`- Cation EXCHANGER. Replaces `Ca^(2+)` ION

Discussion

12.	Hard water is not fit for washing clothes because :
Answer» It contains `Na_2SO_4` and KCl It GIVES precipitate with soap It contains impurities It is ACIDIC in nature Answer :B

Discussion

13.	Hard water contains
Answer» `Mg^(++) and Na^(+) IONS` `Mg^(++) and K^(+) ions` `Mg^(++) and Ca^(+) ions` `Mg^(++) and Ba^(+) ions` Answer :C

Discussion

14.	Hard water becomes free from ____ions when passed through ion exchange resin containing RCOOH groups:
Answer» `CL^-` `SO_4^2-` `H_3O^+` `CA^(2+)` ANSWER :D

Discussion

15.	Hard steel contains :
Answer» No CARBON `0.6 - 1.5%` carbon `5%` carbon `0.5-0.2%` carbon ANSWER :B

Discussion

16.	Hard soap are :
Answer» SODIUM salts of HIGHER FATTY ACIDS Potassium salts of higher fatty acids CALCIUM salts of higher fatty acids Magnesium salts of higher fatty acids Answer :A

Discussion

17.	Halolkanes and haloarenes are compounds containing halogen atom. They undergo many types of reaction. Identity the product formed in the following reaction : CH_3-CH_2-CH_2Cl overset(alc KOH)rarr
Answer» `CH_3-CH_2-CH_2-OH` `CH_3CH = CH_2` `CH_3C EQUIV CH` SOLUTION :`CH_3-CH=CH_2`

Discussion

18.	Halogens have maximum negative electron gain enthalpy in the respective periods of the periodic table. Why ?
Answer» Solution :HALOGENS have the smallest size in their respective periods and THEREFORE high EFFECTIVE nuclear CHARGE. As a consequence, they readily accept one ELECTRON to acquire noble gas configuration.

Discussion

19.	Which of the followingwill have the most negative electron gain enthalpy and which the least negative ? P,S,Cl,F. Explain your answer.
Answer» Solution :Halogens have SMALLER size in their periods. Halogens need only one more ELECTRON to ATTAIN noble gas configuration. So halogens have HIGH negative electron gain rnthaply

Discussion

20.	Halogens have maximum negative electron gain enthalpy. Explain why ?
Answer» Solution :Halogens have the smallest size in their respective PERIODS and, therefore, have high effective nuclear charge. As a result, they readily ACCEPT one electron to acquire the stable ELECTRONIC configuration of the nearest noble gas. In other words, large amount of energy is released when a halogen atom accepts and electron to form the corresponding halide ION and thus halogens have maximum negative electron GAIN enthalpies.

Discussion

21.	Halogens exist in -1, +1, +3, +5 " and " +7 oxidation states. The only halogen which exists in -1 oxidation state is :
Answer» F Cl Br I Solution :F EXISTS in only `-1` OXIDATIN STATE.

Discussion

22.	Halogens combine with each other to form interhalogen compounds (XX', XX'_(3), XX'_(5) and XX'_(7)). Halide ions often react with molecules of halogens or interhalogens to form polyhalide ions consisting either of the same halogen or of two or three different halogens. Besides these, a few othe anions are known, which do not contain any of the halogen atoms but behave like halide ions. These anions are called pseudohalides and consist of two of more atoms of which one is always a nitrogen atom. The correct order of pseudohalide, polyhalide and interhalogen are
Answer» `BrI_(2)^(-), OCN^(-), IF_(5)` `IF_(5), BrI_(2)^(-), OCN^(-)` `OCN^(-), IF_(5), BrI_(2)^(-)` `OCN^(-), BrI_(2)^(-), IF_(5)` Solution :`OCN^(-)` (PSEUDOHALIDE), `BrI_(2)^(-)` (POLYHALIDE), `IF_(5)` (INTERHALOGEN).

Discussion

23.	Halogens combine with each other to form interhalogen compounds (XX', XX'_(3), XX'_(5) and XX'_(7)). Halide ions often react with molecules of halogens or interhalogens to form polyhalide ions consisting either of the same halogen or of two or three different halogens. Besides these, a few othe anions are known, which do not contain any of the halogen atoms but behave like halide ions. These anions are called pseudohalides and consist of two of more atoms of which one is always a nitrogen atom. The isoelectronic pair is
Answer» `Cl_(2), O, ICl_(2)^(-)` `ICl_(2)^(-), ClO_(2)` `IF_(2)^(+), I_(3)^(-)` `ClO_(2)^(-), ClF_(2)^(+)` Solution :Both `ClO_(2)^(-) (17 + 2 xx 8 + 1) and CIF_(2)^(+) (17 + 2 xx 9 - 1)` have 34 ELECTRONS.

Discussion

24.	Halogens do not occur free in nature. Explain.
Answer» SOLUTION :Because HALOGENS are HIGHLY REACTIVE

Discussion

25.	Halogens combine with each other to form interhalogen compounds (XX', XX'_(3), XX'_(5) and XX'_(7)). Halide ions often react with molecules of halogens or interhalogens to form polyhalide ions consisting either of the same halogen or of two or three different halogens. Besides these, a few othe anions are known, which do not contain any of the halogen atoms but behave like halide ions. These anions are called pseudohalides and consist of two of more atoms of which one is always a nitrogen atom. Which one of the following is not a pseudohalide ?
Answer» `CNO^(-)` `RCOO^(-)` `OCN^(-)` `NNN^(-)` SOLUTION :`RCOO^(-)` does not contain a N atom and HENCE is not a PSEUDOHALIDE.

Discussion

26.	Halogens are volatile because :
Answer» they are all covalent molecules they possess high boiling points they are held TOGETHER by weak VAN DER WAALS forces they are stable at room temperature. Answer :C

Discussion

27.	Halogens combine among themselves to form covalent compounds which are called
Answer» PSEUDOHALIDES INTERHALOGEN compounds Polyhalides None of these Answer :B

Discussion

28.	Halogens can be estimated by:
Answer» DUMA's METHOD CARIUS method Leibig's mehtod None of these Answer :B

Discussion

29.	Halogens are strong ............ agents because of their high ................
Answer» SOLUTION :OXIDISING, ELECTRON GAIN ENTHALPY

Discussion

30.	Why are halogens strong oxidising agents?
Answer» SOLUTION :OXIDISING, ELECTRON GAIN ENTHALPY

Discussion

31.	Halogens are highly reactive ? Explain.
Answer» Solution :Halogens have seven electrons in their respective valence SHELLS and thus need only ONE more electron to COMPLETE their respective octets. That is why halogens are very REACTIVE.

Discussion

32.	Halogens are placed in the VIIA group or gp 17 because
Answer» They are non-metals They are very reactive They are electronegative They have 7 ELECTRONS in outernmost orbit Answer :D

Discussion

33.	Halogens are coloured because
Answer» their atoms have high electronegativity their molecules are held to together by WEAK van der Waal's forces their molecules ABSORB visible LIGHT causing the EXCITATION of outer electrons to higher ENERGY levels their atoms absorb energy causing the excitation of outer electrons to higher energy levels Answer :C

Discussion

34.	Halogens are
Answer» Diatomic monoatomic Polyatomic Triatomic Answer :A

Discussion

35.	Halogenation of silver salt of carboxylic acid using CCl_4 as solvent to form alkylhalide is an example of :
Answer» FREE RADICAL HALOGENATION NUCLEAR halogenation Hunsdiecker reaction HVZ reaction Answer :C

Discussion

36.	Halogenationof nitroparaffinsis thecharacteristic reactionof
Answer» `ALPHA` - H atoms `BETAH` atoms `GAMMA- H` atoms `DELTA - H` atoms Answer :A

Discussion

37.	Halogenation of silver salt of carboxylic acid using C Cl_4 as solvent to form alkylhalide is an example of :
Answer» FREE radical halogenation Nuclear halogenation Hunsdiecker reaction HVZ reaction Answer :C

Discussion

38.	Halogenation of anisole is carried in the presence of catalyst
Answer» `FeCl_3` `AlCl_3` `BF_3` `CH_3COOH` ANSWER :D

Discussion

39.	Halogenation of an alkene is a /an-
Answer» SUBSTITUTION REACTION elimination reaction addition reaction OXIDATION reaction Answer :C

Discussion

40.	Halogenation of alanes is
Answer» a reductive process on oxidative process. an isothermal process an indothermal process Solution :We know that before halogenation, the electron pair constituting the C-H bond is almost due to samll difference in their electronegativity VALUES. And after halogenation,the ELECTORN pair of the C-H bond is NEAR to the halogen atomm. Thus carbon ATOMS looses its some SHARE in the electron pair and hence said to be oxidised.Therefore halogenation of alkanes is an oxidative process

Discussion

41.	Halogenation of alkanes is not a good method of preparation of alkyl halides. Explain.
Answer» Solution :(1) Direct fluorination of alkanes is HIGHLY exothermic, explosive and invariably leads to polyfluorination and decomposition of the alkanes. It is difficult to contrl the reaction. (2) Direct iodination of alkanes is highly REVERSIBLE and difficult to carry out. (3) In direct chlorination and bromination, the reaction is not selective. It can lead to different isomeric monohalogenated alkanes (alkyl halides) as well as POLYHALOGENATED alkanes. Hence, halogenation of alkanes is not a good METHOD of PREPARATION of alkyl halides.

Discussion

42.	Halogen with highest bond energy
Answer» `F_(2)` `Cl_(2)` `Br_(2)` `I_(2)` Solution :BOND dissociation energy `=Cl_(2)gtBr_(2)gt F_(2)gtI_(2)`

Discussion

43.	Halogen used in the preparation of insecticides is:
Answer» `I_2` `Cl_2` `Br_2` `F_2` ANSWER :B

Discussion

44.	Halogen used as an antiseptic is:
Answer» Fluroine Chlorine Bromine Iodine Answer :D

Discussion

45.	Halogen molecules are
Answer» DIATOMIC and FORM diatomic and form X ions monoatomic and form X- monoatomic and form X, ions Answer :B

Discussion

46.	Halogen derivatives of alkane is known as
Answer» ALKYL HALIDES alkenyl halides alkynyl halides aralkyl halides Answer :A

Discussion

47.	Halogen molecules are:
Answer» MONOATOMIC and FORM `X_2^(2-)` ions Diatomic and form `X^-` ions Diatomic and form `X_2^(2-)` ions Monoatomic and form `X^-` ions Answer :B

Discussion

48.	Halogen are coloured, because
Answer» they are strong oxidant. their molecules are held together by weak vander WAALS forces their atoms absorb radiations from visible range CAUSING the excitation of valence ELECTRONS to higher energy levels. their molecules absorb light RADIATION forming the excited states. Answer :D

Discussion

49.	Halogen acids react with alcohols to form alkyl halides. The reaction follows a nucleophilic substitution mechanism. What will be the major product of the following reaction? CH_3-overset(CH_3)overset(\|)(CH)-underset(OH)undeset(\|)(CH)-CH_3+HCl to
Answer» `CH_3underset(CH_3)underset(\|)(CH)-underset(CL)underset(\|)(CH_3)` `CH_3underset(Cl)underset(\|)(CH)-underset(CH_3)underset(\|)(CH)-CH_3` `CH_3-underset(Cl)underset(\|)overset(CH_3)overset(\|)(C)-CH_2CH_3` `CH_3CH_2CH_2CH_2CH_2Cl` Solution :`CH_3overset(CH_3)overset(\|)(CH)underset(OH)underset(\|)(CH)CH_3+HCl tounderset(2^@ "carbocation")(CH_3overset(CH_3)overset(\|)CHoverset(+)CHCH_3)underset("shift")overset(1,2-"HYDRIDE")to` `underset(3^@ "carbocation")(CH_3overset(CH_3)overset(\|)overset(+)C CH_3)overset(Cl^(-))toCH_3underset("MAJOR")underset(Cl)underset(\|)overset(CH_3)overset(\|)(C C)H_2CH_3+CH_3underset("Minor")underset(CH_3)underset(\|)(CH)underset(Cl)underset (\|)(CH)CH_3`

Discussion

50.	Halogen acid used in the preparation of aquaregia is:
Answer» HF HBr HCl HI Answer :C

Discussion

Explore topic-wise InterviewSolutions in Current Affairs.

HeLa cells used in cell biology are

Helium and neon do not form compounds with fluorine. Why ?

Hardness of transition elements is due to :

Heisenberg's uncertainty principle cannot be applied to stationary electron. Why?

Heisenberg uncertainty principle precludes the simultaneous measurement of

Heavy water posseses:

Hardest s-block metal is-

Hardest element of group 13 is:

Hardening of oils is caused by

Hardening of leather in tanning industry is based on

Hard water when passed through ion exchange resin containing RCOOH group, becomes free from

Hard water is not fit for washing clothes because :

Hard water contains

Hard water becomes free from ____ions when passed through ion exchange resin containing RCOOH groups:

Hard steel contains :

Hard soap are :

Halolkanes and haloarenes are compounds containing halogen atom. They undergo many types of reaction. Identity the product formed in the following reaction : CH_3-CH_2-CH_2Cl overset(alc KOH)rarr

Halogens have maximum negative electron gain enthalpy in the respective periods of the periodic table. Why ?

Which of the followingwill have the most negative electron gain enthalpy and which the least negative ? P,S,Cl,F. Explain your answer.

Halogens have maximum negative electron gain enthalpy. Explain why ?

Halogens exist in -1, +1, +3, +5 " and " +7 oxidation states. The only halogen which exists in -1 oxidation state is :

Halogens do not occur free in nature. Explain.

Halogens are volatile because :

Halogens combine among themselves to form covalent compounds which are called

Halogens can be estimated by:

Halogens are strong ............ agents because of their high ................

Why are halogens strong oxidising agents?

Halogens are highly reactive ? Explain.

Halogens are placed in the VIIA group or gp 17 because

Halogens are coloured because

Halogens are

Halogenation of silver salt of carboxylic acid using CCl_4 as solvent to form alkylhalide is an example of :

Halogenationof nitroparaffinsis thecharacteristic reactionof

Halogenation of silver salt of carboxylic acid using C Cl_4 as solvent to form alkylhalide is an example of :

Halogenation of anisole is carried in the presence of catalyst

Halogenation of an alkene is a /an-

Halogenation of alanes is

Halogenation of alkanes is not a good method of preparation of alkyl halides. Explain.

Halogen with highest bond energy

Halogen used in the preparation of insecticides is:

Halogen used as an antiseptic is:

Halogen molecules are

Halogen derivatives of alkane is known as

Halogen molecules are:

Halogen are coloured, because

Halogen acids react with alcohols to form alkyl halides. The reaction follows a nucleophilic substitution mechanism. What will be the major product of the following reaction? CH_3-overset(CH_3)overset(|)(CH)-underset(OH)undeset(|)(CH)-CH_3+HCl to

Halogen acid used in the preparation of aquaregia is: