Subject

Chemistry

Class

JEE Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

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21.

The oxidation states of Cr in [Cr(H2O)6]Cl3,[Cr(C6H6)2], and K2[Cr(CN)2 (O)2(O2)(NH3)] respectively are :

  • +3, +2, and +4

  • +3, 0, and +6

  • +3, 0, and +4

  • +3, +4, and +6


B.

+3, 0, and +6

(i) [Cr(H2O)6]Cl3:Hexaaquachromium(III) chloride
x + 6 × 0 + (–1) × 3 = 0
x = +3

(ii) [Cr(C6H6)2] : bis(h6–benzene)chromium(0)
y + 2 × 0 = 0
y =0 =
(iii) K2[Cr(CN)2 (O)2 (O2) (NH3)] :

Potassium amminedicyanidodioxidoperoxidochromate(VI)
2 × 1 + z + 2 × (–1) + 2 × (–2) + (–2) + 0 = 0
z = +6

The oxidation states of Cr in [Cr(H2O)6]Cl3, [Cr(C6H6)2], and K2 [Cr(CN)2 (O)2 (O2) (NH3)]
respectively are +3, 0 and +6.


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22.

Which of the following compounds will be suitable for Kjeldah1’s method for nitrogen estimation?


23.

Glucose on prolonged heating with HI gives

  • 6-iodohexanal

  • n-Hexane

  • 1-Hexene

  • Hexanoic acid


24.

The increasing order of basicity of the following compounds is:

  • (d) < (b) < (a) < (c)

  • (a) < (b) < (c) < (d)

  • (b) < (a) < (c) < (d)

  • (b) < (a) < (d) < (c)


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25.

Phenol reacts with methyl chloroformate in the presence of NaOH to form product A. A reacts with Br2 to form product B. A and B are respectively:


26.

The major product formed in the following reaction is:


27.

Phenol on treatment with CO2 in the presence of NaOH followed by acidification produces compound X as the major product. X on treatment with (CH3CO)2O in the presence of catalytic amount of H2SO4 produces:


28.

The major product of the following reaction is,


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29.

The compound that does not produce nitrogen gas by the thermal decomposition is

  • (NH4)2SO4

  • Ba(N3)2

  • (NH4)2Cr2O7

  • NH4NO2


30.

Which of the following salts is the most basic in aqueous solution?

  • Pb(CH3COO)2

  • Al(CN)3

  • CH3COOK

  • FeCl3


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