94420 + Interview Questions in Chemistry in Class 12

1.	HF is a weaker acid than HCl why?
Answer» SOLUTION :SINCE `H-F` bond is STRONGEST, hence it is weakest ACID AMONG all the halogen acids.

Discussion

2.	Heating a mixture of ethyl alcohol acetic acid in presence of conc. H_2SO_4produces a fruity smelling compounds A . Then A is
Answer» ETHER ESTER Aldehyde KETONE ANSWER :B

Discussion

3.	HF is a weak acid but HCl is a strong acid because
Answer» HF ATTACKS glass but HCl does not HF is less ionic than HCl Electron affinity of fluorine is LOWER than chlorine BOND energy of HF is higher than HCl Solution :Bond energy of H-F is higher than HCl

Discussion

4.	Heat treatment alters the properties of steel due to
Answer» chemical reaction on heating partial rusting change in the RESIDUAL energy change in the lattice STRUCTURE due to differential rate of cooling Solution :Heat treatment alters the PROPERTIES of STEEL due to rearrangement of its grain structure.

Discussion

5.	Hexane dioic acid in obtained by oxidation of
Answer» BENZENE CYCLOHEXANE CYCLOHEXENE cyclohexane carbaldehyde ANSWER :C

Discussion

6.	Heat required to raise the temperature of 1 mol of a substance by 1^(@)C is called
Answer» SPECIFIC HEAT MOLAR heat CAPACITY Water EQUIVALENT Specific gravity Solution :It is molar heat capacity.

Discussion

7.	Heat produced in calories by the combustion of one gram of carbon is called
Answer» Heat of COMBUSTION of CARBON Heat of FORMATION of carbon CALORIFIC value of carbon Heat of production of carbon. Solution :It is the definition of calorific value.

Discussion

8.	Hexane, C_(6)H_(14), is immiscible with water and ethanol. Water and ethanol are miscible. C_(6)H_(14)has the lowes density. Which diagram represents the results when equal volumes of these three liquids are placed in a test tube and shaken?
Answer» 1 2 3 4 Answer :D

Discussion

9.	Heat of transition is the heat evolved or absorbed when a substance is converted from
Answer» Solid to liquid Solid to vapour Liquid to vapour One ALLOTROPIC form to another allotropic form SOLUTION :It is the definition of heat of TRANSITION.

Discussion

10.	Calculate the entropy change involved in the conversion of one mole of water at 373 K to vapour at the same temperature.(Latent heat of vaporisation of water at this temperature , Delta H_vap = 2.257 kJg^-1)
Answer» ANSWER :C

Discussion

11.	Hexamethylenediamine and adipic acid are monomers of ……………………
Answer» SOLUTION :NYLON - 6, 6

Discussion

12.	Heat of reaction of which of the following equation expresses the bond energy of HCl :-
Answer» `HCl(G)toH(g)+CL(g)` `2HCl(g) to H_(2)(g)+Cl_(2)(g)` `HCl(g)to(1)/(2)H_(2)(g)+(1)/(2)Cl_(2)(g)` `HCl(g)toH^(+)(g)+Cl^(-)(g)`. Answer :A

Discussion

13.	Heat of reaction is the change in enthalpy or internal energy as represented by a balanced thermochemical equation. The amount of energy released during a chemical change depends upon the state of reactants and products, the conditions of pressure and volume at which reaction is carried out, and temperature. The variation of heat of reaction (Delta H or Delta E) with temperature is given as DeltaH_(2) - Delta H_(1) = Delta C_(p) [T_(2) - T_(1)] or Delta E_(2) - Delta E_(1) = Delta C_(v) (T_(2) - T_(1)) . Standard heat enthalpy of elements in their most stable state is assumed to be zero whereas standard heat enthalpy of compound is referred as heat of formation of that compound at 1 atm pressure and 25^(@)C . Oxidation of N_(2) to N_(2) O , NO , NO_(2) showsabsorption of energy whereas heat of combustion of N_(2) is exothermic like other heat of combustion. The specific heat of I_(2) in vapour and solid state are 0.031 and 0.55 cal/ g-^(@) C respectively . If heat of sublimation of iodine is 6.096 kcal mol^(-1) at 200 ^(@) C , the heat of sublimation of I_(2) at 250^(@) C is :
Answer» `5.8 KCAL MOL^(-1)` `2.28 kcal mol^(-1)` `4.8 kcal mol^(-1)` `3.8 kcal mol^(-1)` ANSWER :A

Discussion

14.	Heat of reaction is the change in enthalpy or internal energy as represented by a balanced thermochemical equation. The amount of energy released during a chemical change depends upon the state of reactants and products, the conditions of pressure and volume at which reaction is carried out, and temperature. The variation of heat of reaction (Delta H or Delta E) with temperature is given as DeltaH_(2) - Delta H_(1) = Delta C_(p) [T_(2) - T_(1)] or Delta E_(2) - Delta E_(1) = Delta C_(v) (T_(2) - T_(1)) . Standard heat enthalpy of elements in their most stable state is assumed to be zero whereas standard heat enthalpy of compound is referred as heat of formation of that compound at 1 atm pressure and 25^(@)C . Oxidation of N_(2) to N_(2) O , NO , NO_(2) showsabsorption of energy whereas heat of combustion of N_(2) is exothermic like other heat of combustion. Heat of vaporisation of H2O is 627.78 cal/g. If heat of formation of H_(2) O_((l)) is -68.3 kcal , heat of formation of H_(2) O_((g)) is :
Answer» `-57.0` KCAL `559.5` kcal `676.73` kcal Can not be CALCULATED ANSWER :A

Discussion

15.	Hexamethylene tetramine is used as an:
Answer» ANALGESIC Antipyretic Urinary antiseptic All Answer :C

Discussion

16.	Heat of reaction is the change in enthalpy or internal energy as represented by a balanced thermochemical equation. The amount of energy released during a chemical change depends upon the state of reactants and products, the conditions of pressure and volume at which reaction is carried out, and temperature. The variation of heat of reaction (Delta H or Delta E) with temperature is given as DeltaH_(2) - Delta H_(1) = Delta C_(p) [T_(2) - T_(1)] or Delta E_(2) - Delta E_(1) = Delta C_(v) (T_(2) - T_(1)) . Standard heat enthalpy of elements in their most stable state is assumed to be zero whereas standard heat enthalpy of compound is referred as heat of formation of that compound at 1 atm pressure and 25^(@)C . Oxidation of N_(2) to N_(2) O , NO , NO_(2) showsabsorption of energy whereas heat of combustion of N_(2) is exothermic like other heat of combustion. Which statements regarding the formation of NO and NO_(2) respectively from N_(2) and O_(2) are correct : (A) Heat of formation of NO is exothermic (B) Heat of formation of NO_(2) is exothermic (C) The oxidation of N_(2) to NO and NO_(2) is favoured at high temperature. (D) If heat of formation of NO and NO_(2) are 21.55 and 8.50 kcal, heat of reaction for NO + (1)/(2) O_(2) to NO_(2) is -13.05 kcal
Answer» 1, 2 3 , 4 1 ,2 , 4 1, 2 , 3 ANSWER :B

Discussion

17.	Hexagonal close packing is found in crystal lattice of :
Answer» Na Mg Al None of these Answer :A

Discussion

18.	Heat of reaction is the change in enthalpy or internal energy as represented by a balanced thermochemical equation. The amount of energy released during a chemical change depends upon the state of reactants and products, the conditions of pressure and volume at which reaction is carried out, and temperature. The variation of heat of reaction (Delta H or Delta E) with temperature is given as DeltaH_(2) - Delta H_(1) = Delta C_(p) [T_(2) - T_(1)] or Delta E_(2) - Delta E_(1) = Delta C_(v) (T_(2) - T_(1)) . Standard heat enthalpy of elements in their most stable state is assumed to be zero whereas standard heat enthalpy of compound is referred as heat of formation of that compound at 1 atm pressure and 25^(@)C . Oxidation of N_(2) to N_(2) O , NO , NO_(2) showsabsorption of energy whereas heat of combustion of N_(2) is exothermic like other heat of combustion. Standard heat enthalpy has been assumed to be zero for :
Answer» GRAPHITE DIAMOND CHARCOAL LAMP black Answer :A

Discussion

19.	Hexamethylene tetramine is commonly known as _____.
Answer» UROTROPINE Methenamine Hexamine All of the above Solution :Urotropine

Discussion

20.	Heat of reaction for, CO(g) 1/2 O_(2)(g) rarr CO_(2)(g) at constant V is -67.71 kcal at 17^(@)C. The heat of reaction at constant P at 17^(@)C
Answer» `+68.0` KCAL `-67.42` kcal `-68.0` kcal None Answer :C

Discussion

21.	Hexaflurocobaltate (III) ion is found to be high spin complex, the probable hybrid state of cobalt in it is:
Answer» `d^2sp^3` `sp^3` `sp^3d` `sp^3d^2` ANSWER :D

Discussion

22.	Heat of reaction at constant volume is measured in the apparatus
Answer» Bomb calorimeter Calorimeter Pyknometer Pyrometer Solution :Both calorimeter is USED to MEASURE HEAT of REACTION.

Discussion

23.	'Heat ofneutralisation of a strong dibasic acid in dilute solution by NaOH is'
Answer» `-27.4 cal/equ `-13.7 cal/equ `+13.7 cal/equ `-13.7 cal/mol Answer :B

Discussion

24.	Heat of neutralization of the acid-base reaction is 57.32 kJ for
Answer» `HNO_(3)+LIOH` HCOOH+KOH `HCl+NH_(4)OH` `CH_(3)COOH+NaOH` SOLUTION :Strong ACID `(HNO_(3))` and strong base (LiOH).

Discussion

25.	Heat of neutralization will be minimum for which of the following combination
Answer» `NaOH+H_(2)SO_(4)` `NH_(4)OH+CH_(3)COOH` `NaOH+HCl` `NaOH+CH_(3)COOH` SOLUTION :Heat of neutralization is the heat liberated when one mole acid is neutralized by base. For strong acid-strong base neutralization, its VALUE is 57kJ/mol. For weak acid or base its value is less than this value. Hence, the heat of neutralization will be MINIMUM for `CH_(3)COOH+NH_(4)OH`.

Discussion

26.	Heat of neutralization of the reaction, NaOH+HCl rarr NaCl + H_(2)O is 57.2"kJ mol"^(-1). What will be the heat released when 0.25 mole of NaOH is titrated against 0.25 mole of HCl
Answer» 28.6 kJ 57.1 kJ 14.3 kJ 22.5 kJ Answer :C

Discussion

27.	Heat of neutralization of strong acid and weak base is
Answer» 57.1 kJ `mol^(-1)` 13.7 kJ `mol^(-1)` Less than 13.7 kcal `mol^(-1)` More than 13.7 kcal `mol^(-1)` Solution :HEAT of neutralization of strong ACID and WEAK BASE is less than 13.7 kcal `mol^(-1)`.

Discussion

28.	Heat of neutralisation of strong acid and strong base under 1 atm and 25^@C is -13.7 kcal. If standard Gibbs energy change for dissociation of water to H^+ and OH^- is -19.14 kcal, the change in standard entropy for dissociation of water is:
Answer» 18.25 110.2 `-18.25` NONE of these Answer :B

Discussion

29.	Heat of neutralization of strong acid against strong base is constant and is equal to
Answer» 13.7 KCAL 57 kcal `5.7xx10^(4)` J All of the above Solution :13.7 kcal = 57 KJ = `5.7xx10^(4)J`.

Discussion

30.	Heat of neutralization of an acid by a base is highest when
Answer» Both the acid and BASE are WEAK Both the acid and base are STRONG The acid is strong and the base is weak The acid is weak and the base is strong Solution :When both acid and base are strong than heat of neutralization is `57.1 KJ mol^(-1)`.

Discussion

31.	Heat of neutralization of strong acid by a strong base is a constant value due to:
Answer» Salt FORMED does not hydrolyse Only `H^(+)` and `OH^(-)` IONS react in EVERY case The STRONG base and strong acid react completely The strong base and strong acid react in aqueous solution Solution :In neutralization of a strong acid and base only `H^(+)` and `OH^(-)` ions react.

Discussion

32.	Hexafluorocobaltate (III) ion is found to be high spin complex, the probable hybrid state of cobalt in it is:
Answer» `d^2sp^3` `sp^3` `sp^3d` `sp^3d^2` ANSWER :D

Discussion

33.	Heatof neutralization of HF is
Answer» ` GT 57.32J` `LT 57.32 J` `57.23 J` NONE ANSWER :A

Discussion

34.	Heat of neutralisation of weak acid and strong base is less than the heat of neutralisationof strong acid and strong base due to
Answer» Energy has to be SPENT for the total dissociation of WEAK ACID Salt of weak acid and strong base is not stable Incomplete dissociation of weak acid Incomplete neutralisation of weak acid SOLUTION :Energy has to be spent for the total dissociation of weak acid.

Discussion

35.	Heat of neutralization (DeltaH) of NH_(4)OH and HF are -51.5 and -68.6 kJ respectively. Calculate their heat of dissociation? (i) HCl (aq)+NaOH(aq) rarr NaCl (aq)+H_(2)O, ""DeltaH= -57.3 kJ (ii) HCl (aq)+underset("(weak base)")(NH_(4)OH (aq)) rarr NH_(4)Cl (aq)+H_(2)O, ""DeltaH= -51.5 kJ
Answer» Solution :`:.` The HEAT of DISSOCIATION of `NH_(4)OH`, `DELTAH=-51.5-(-57.3)=5.8 kJ` SIMILARLY we have `HF(aq) +NAOH(aq) rarr NaF(aq)+H_(2)O, DeltaH=-68.6 kJ` `:.` The heat of diffociation of `HF`, `DeltaH =-68.6-(-57.3)=-11.3 kJ`

Discussion

36.	Hexafluorferrate(III)ion is an outer orbital complex. The number of unpaired electrons present in.it is:
Answer» 1 5 4 Unpredictable ANSWER :B

Discussion

37.	Heat of neutralisation of weak acid and strong base is less than the heat of neutralisation of strong acid and strong base due to
Answer» A) energy has to be spent for the total dissociation of WEAK acid B) SALT of weak acid and strong base is not stable C) incomplete dissociation of weak acid D) incomplete neutralisation of weak acid Solution :Heat of neutralisation is the change in enthalpy when one gram equivalent of an acid is neutralised by a base or vice versa. All strong acids and bases are almost completely ionised to enthalpy of neutralisation of all strong acids by strong bases are same. weak acids do not undergo complete ionisation IMMEDIATELY on dissolution in WATER. these GET ionised during the reaction of neutralisation. a part of heat evolved during neutralisation is consumed in causing complete ionisation of weak acid. as a result the heat of neutralisation of weak acid with a strong base is less than the heat of neutralisation of stong acid with strong base.

Discussion

38.	Hexaamminenickel(II) hexanitrocobaltate (III) can be written as :-
Answer» `[NI(NH_3)_6[Co(NO_2)_6]` `[Ni(NH_3)_6]_3[Co(NO_2)_6]_2` `[Ni(NH_3)_6][Co(NO_2)_6]` `[Ni(NH_3)_6(NO_2)_6]Co` ANSWER :B

Discussion

39.	Hexa methylene tetramine is used as ............
Answer» analgesic antipyretic URINARY ANTISEPTIC all of these SOLUTION :Urinary antiseptic

Discussion

40.	Heat of neutralisation of a strong acid and strong base is always.
Answer» 13.7 kcal/mole 9.6 kacl/mole 6 kcal/mole 11.4 kacl/mole Answer :A

Discussion

41.	Heat of hydrogenation of cyclohexene to cyclohexane is -28.6 kcal/mol.The observed heat of hydrogenation of benzene to cyclohexane is -49.8 kcal/mol. Calculate the resonance energy of benzene in kcal/mole.
Answer» SOLUTION :RESONANCE ENERGY =-49.8-(-3x28.6)=36 K cal/mol

Discussion

42.	Hexa-2-ene-4-yne is
Answer» `CH_(3)-CH_(2)-C-=C-CH = CH_(2)` `CH_(3)-C-=C-CH=CH-CH_(3)` `CH_(3)CH_(2)-CH=CH-C-=CH` `CH_(3)-C-=C-CH_(2)-CH=CH_(2)` SOLUTION :`UNDERSET("Hexa-2-ene-4-yne")(CH_(3)-C-=C-CH=CH-CH_(3))`

Discussion

43.	Heat of formation of SO_(4) is -298 kJ. What is the heat of combustion of 4g of S
Answer» `+37` KJ `-37.25` kJ `+298` kJ 18.6 kJ Solution :`S+O_(2)rarrSO_(2), DeltaH=-298 kJ` HEAT of formation of `SO_(2)` is also the heat of combustion of sulphur. `because` heat of combustion of 32 g S = (-298) kJ `THEREFORE` heat of combustion of 4g `S=((-298)xx4)/(32)=-37.25 kJ`.

Discussion

44.	Heat of formation of SO_(2) is -298 kJ. What is the heat of combustion of 4 g of S?
Answer» `+37kJ` `-37.25 kJ` `+298kJ` `18.6kJ` Solution :Heat of combustion is TOTAL heat changes accompanying when ONE mole of substance undergoes complete combustion in EXCESS of oxygen. `S+O_(2) to SO_(2),DeltaH=298kJ` `therefore`Heat of formation of `SO_(2)`=heat of combustion of `SO_(2)` atomic mass of S=32G `because`Combustion of 32g of S(=1 mole of S) gives heat =-298 kJ `therefore `Combustion of 4g of S gives heat`=(-298)/(32)xx4=-37.25kJ`.

Discussion

45.	Heteropolymer.
Answer» Solution :A polymer made from more than one kind of repeating UNIT of monomers is called HETEROPOLYMER. The heteropolymers are also called co-polymers. E.g. Terylene, Nylon - 6, 6 , BUNA - S, Buna -N.

Discussion

46.	Heteropoly acids are formed by:
Answer» Be Fe Mo Cr Answer :C

Discussion

47.	Heat of formation of SO_2 "is" -298 kJ. What is the heat of formation of 4 g of SO_2?
Answer» `+37`KJ `-37.15`kJ `+298`kJ `-18.6`kJ Answer :D

Discussion

48.	heat of formation ofH_(2)O is -188 kJ // mol and H_(2)O_(2) is -286 kJ // mol . The enthaply change for thereaction2H_(2)O_(2) to 2H_(2)O+O_(2) is
Answer» 196 kJ `-196 kJ` 984 kJ `-984 kj` Solution :`H_(2)+1/2 O_(2)to H_(2)O,DeltaH=-188kJ mol^(-1)` `H_(2) + O_(2) toH_(2)O_(2) , DeltaH =286 kJ mol ^(-1)` multiply Eqs.(i) and (ii) by 2 `2H_(2)+O_(2) to 2H_(2)O, DeltaH=-376 kJ mol^(-1)` `2H_(2)+2O_(2) to 2H_(2)O_(2) , DeltaH =- 572 kJ mol^(-1)` Eq .(iii) - Eq.(iv) `2H_(2)O_(2) to 2H_(2)O + O_(2), DeltaH_(r) =+196 kJ`

Discussion

49.	Heterolytic cleavage of a covalent bond gives only:
Answer» CATIONIC species Anionic species Both of the above Free radicals Answer :C

Discussion

50.	Heterolytic bond dissociation energy of alkyl halides follows the sequence
Answer» `R-F GT R -Cl gt R -BR gt R -I` `R - I gt R - Br gt R - Cl gt R - F` `R - I gt R - F gt R - Br gt R - Cl` `R - Cl gt R - Br gt R- I gt R - F` Solution :`R-I gt R - Br gt R - Cl gt R - F`

Discussion

Explore topic-wise InterviewSolutions in Current Affairs.

HF is a weaker acid than HCl why?

Heating a mixture of ethyl alcohol acetic acid in presence of conc. H_2SO_4produces a fruity smelling compounds A . Then A is

HF is a weak acid but HCl is a strong acid because

Heat treatment alters the properties of steel due to

Hexane dioic acid in obtained by oxidation of

Heat required to raise the temperature of 1 mol of a substance by 1^(@)C is called

Heat produced in calories by the combustion of one gram of carbon is called

Hexane, C_(6)H_(14), is immiscible with water and ethanol. Water and ethanol are miscible. C_(6)H_(14)has the lowes density. Which diagram represents the results when equal volumes of these three liquids are placed in a test tube and shaken?

Heat of transition is the heat evolved or absorbed when a substance is converted from

Calculate the entropy change involved in the conversion of one mole of water at 373 K to vapour at the same temperature.(Latent heat of vaporisation of water at this temperature , Delta H_vap = 2.257 kJg^-1)

Hexamethylenediamine and adipic acid are monomers of ……………………

Heat of reaction of which of the following equation expresses the bond energy of HCl :-

Hexamethylene tetramine is used as an:

Hexagonal close packing is found in crystal lattice of :

Hexamethylene tetramine is commonly known as _____.

Heat of reaction for, CO(g) 1/2 O_(2)(g) rarr CO_(2)(g) at constant V is -67.71 kcal at 17^(@)C. The heat of reaction at constant P at 17^(@)C

Hexaflurocobaltate (III) ion is found to be high spin complex, the probable hybrid state of cobalt in it is:

Heat of reaction at constant volume is measured in the apparatus

'Heat ofneutralisation of a strong dibasic acid in dilute solution by NaOH is'

Heat of neutralization of the acid-base reaction is 57.32 kJ for

Heat of neutralization will be minimum for which of the following combination

Heat of neutralization of the reaction, NaOH+HCl rarr NaCl + H_(2)O is 57.2"kJ mol"^(-1). What will be the heat released when 0.25 mole of NaOH is titrated against 0.25 mole of HCl

Heat of neutralization of strong acid and weak base is

Heat of neutralisation of strong acid and strong base under 1 atm and 25^@C is -13.7 kcal. If standard Gibbs energy change for dissociation of water to H^+ and OH^- is -19.14 kcal, the change in standard entropy for dissociation of water is:

Heat of neutralization of strong acid against strong base is constant and is equal to

Heat of neutralization of an acid by a base is highest when

Heat of neutralization of strong acid by a strong base is a constant value due to:

Hexafluorocobaltate (III) ion is found to be high spin complex, the probable hybrid state of cobalt in it is:

Heatof neutralization of HF is

Heat of neutralisation of weak acid and strong base is less than the heat of neutralisationof strong acid and strong base due to

Heat of neutralization (DeltaH) of NH_(4)OH and HF are -51.5 and -68.6 kJ respectively. Calculate their heat of dissociation? (i) HCl (aq)+NaOH(aq) rarr NaCl (aq)+H_(2)O, ""DeltaH= -57.3 kJ (ii) HCl (aq)+underset("(weak base)")(NH_(4)OH (aq)) rarr NH_(4)Cl (aq)+H_(2)O, ""DeltaH= -51.5 kJ

Hexafluorferrate(III)ion is an outer orbital complex. The number of unpaired electrons present in.it is:

Heat of neutralisation of weak acid and strong base is less than the heat of neutralisation of strong acid and strong base due to

Hexaamminenickel(II) hexanitrocobaltate (III) can be written as :-

Hexa methylene tetramine is used as ............

Heat of neutralisation of a strong acid and strong base is always.

Heat of hydrogenation of cyclohexene to cyclohexane is -28.6 kcal/mol.The observed heat of hydrogenation of benzene to cyclohexane is -49.8 kcal/mol. Calculate the resonance energy of benzene in kcal/mole.

Hexa-2-ene-4-yne is

Heat of formation of SO_(4) is -298 kJ. What is the heat of combustion of 4g of S

Heat of formation of SO_(2) is -298 kJ. What is the heat of combustion of 4 g of S?

Heteropolymer.

Heteropoly acids are formed by:

Heat of formation of SO_2 "is" -298 kJ. What is the heat of formation of 4 g of SO_2?

heat of formation ofH_(2)O is -188 kJ // mol and H_(2)O_(2) is -286 kJ // mol . The enthaply change for thereaction2H_(2)O_(2) to 2H_(2)O+O_(2) is

Heterolytic cleavage of a covalent bond gives only:

Heterolytic bond dissociation energy of alkyl halides follows the sequence