The brown ring test for nitrates depends on : from Chemistry The

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 Multiple Choice QuestionsMultiple Choice Questions

441.

Liquor ammonia bottles are opened only after cooling. This is because

  • it is only a mild explosive

  • it is a corrosive liquid

  • it is a lachrymatory

  • it generates high vapour pressure and mild explosive


442.

When plants and animals decay, the organic nitrogen is converted into inorganic nitrogen. The inorganic nitrogen is in the form of

  • ammonia

  • elements of nitrogen

  • nitrates

  • nitrides


443.

The formation of O2+[PtF6]- is the basis for the formation of xenon fluorides. This is because :

  • O2 and Xe have comparable size

  • Both O2 and Xe are gases

  • O2 and Xe have both comparable ionisation size energies and comparable sizes.

  • O2 and Xe have comparable electro- negativities.


444.

The formula mass of Mohr's salt is 392. The iron present in it is oxidised by KMnO4 in acid medium. The equivalent mass of Mohr's salt is :

  • 392

  • 31.6

  • 278

  • 156


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445.

The brown ring test for nitrates depends on :

  • the reduction of nitrate to nitric oxide

  • oxidation of nitric oxide to nitrogen dioxide

  • reduction of ferrous sulphate to iron

  • oxidising action of sulphuric acid


A.

the reduction of nitrate to nitric oxide

The brown ring is obtained due to the formation of pentaaquanitrosonium ion. In this reaction reduction of nitrate ion by Fe2+ ion takes places as

NO3- + 3Fe2+ + 4H+ NO + 3Fe3+ + 2H2OFe2++ NO+ 5H2O  [Fe(H2O)5NO]2+Brown complex


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446.

An organic compound which produces a bluish green coloured flame on heating in presence of copper is :

  • chlorobenzene

  • benzaldehyde

  • aniline

  • benzoic acid


447.

Acidified sodium fusion extract on addition of ferric chloride solution gives blood red colouration which confirms the presence of

  • S and Cl

  • N and S

  • N

  • S


448.

The number of gram molecules of chlorine in 6.02 × 1025 hydrogen chloride molecules is

  • 10

  • 100

  • 50

  • 5


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449.

When conc. H2SO4 is heated with P2O5, the acid is converted into

  • sulphur trioxide

  • sulphur dioxide

  • sulphur

  • a mixture of sulphur dioxie and sulphur trioxide


450.

The noble gas mixture is cooled in a coconut bulb at 173 K. The gases that are not adsorbed are

  • Ne and Xe

  • He and Xe

  • Ar and Kr

  • He and Ne


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