In basic medium the amount of Ni2+ in a solution can be estimated

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 Multiple Choice QuestionsMultiple Choice Questions

51.

At 25°C, pH of a 10-8 M aqueous KOH solution will be

  • 6.0

  • 7.02

  • 8.02

  • 9.02


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52.

In basic medium the amount of Ni2+ in a solution can be estimated with the dimethylglyoxime reagent. The correct statement(s) about the reaction and the product is (are) 

  • in a ammoniacal solution Ni2+ salts give cherry-red precipitate of nickel (II) dimethylglyoximate

  • two dimethylglyoximate units are bound to one Ni2+

  • in the complex two dimethylglyoximate units are hydrogen bonded to each other

  • each dimethylglyoximate unit forms a six membered chelate ring with Ni2+


A.

in a ammoniacal solution Ni2+ salts give cherry-red precipitate of nickel (II) dimethylglyoximate

B.

two dimethylglyoximate units are bound to one Ni2+

C.

in the complex two dimethylglyoximate units are hydrogen bonded to each other

D.

each dimethylglyoximate unit forms a six membered chelate ring with Ni2+

Estimation of Ni2+ is carried out as.

Filtrate of group III + NH4OH + NH4Cl  passing H2S gas → black ppt of NiS (it is soluble in conc. HCl in presence of oxidising agent like KClO3)

NiS + 2HCl + O → NiCl2 + H2O + S

When NiCl2 in basic medium, treated with dimethyl glyoxime, a cherry red ppt of nickel (II) dimethyl glyoximate is obtained. It consists of 2 dimethyl glyoximate units which are hydrogen bonded to each other and each unit forms a 6-membered ring with Ni2+.


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53.

1 x 10-3 mole of HCl is added to a buffer solution made up of' 0.01 M acetic acid and 0.01 M sodium acetate. The final pH of the buffer (given, pKa of acetic acid is 4.75 at 25°C)

  • 4.60

  • 4.66

  • 4.75

  • 4.8


 Multiple Choice QuestionsShort Answer Type

54.

In 'x' mL 0.3 N HCl, addition of 200 mL distilled water or addition of 100 mL 0.1 N NaOH, gives same final acid strength. Determine 'x'.


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55.

Deep blue CusO4·5H2O is converted to a bluish white salt at 100°C. At 250°C and 750°C it is then transformed to a white powder and black material respectively. Identify the salts.


 Multiple Choice QuestionsMultiple Choice Questions

56.

A 100 mL 0.1 = (M) solution of ammonium acetate is diluted by adding 100 mL of water. The pH of the resulting solution will be (pKa of acetic acid is nearly equal to pKb of NH4OH).

  • 4.9

  • 5.0

  • 7.0

  • 10.0


57.

In a reversible chemical reaction at equilibrium, if the concentration of any one of the reactants is doubled, then the equilibrium constant will

  • also be doubled

  • be halved

  • remains the same

  • becomes one-fourth


58.

The pH of an aqueous solution of CH3COONa of concentration C(M) is given by

  • 7 - 12pKa12log C

  • 12pKw12pKb12log C

  • 12pKw12pKb12log C

  • 12pKw12pKa12log C


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59.

If the equilibrium constants of the following equilibria,

SO212O2 → SO3 and 2SO3 → 2SO2 + O2

are given by K1 and K2 respectively, which of the following realation is correct?

  • K21K12

  • K11K23

  • K21K1

  • K2 = (K1)2


60.

20 mL 0.1 (N) acetic acid is mixed with 10 mL 0.1(N) solution of NaOH. The pH of the resulting solution is (pKa of acetic acid is 4.74)

  • 3.74

  • 4.74

  • 5.74

  • 6.74


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