Subject

Chemistry

Class

JEE Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

21.

The strongest base among the following is

  • Amide ion

  • Hydroxide ion

  • Trimethylamine

  • Ammonia


22.

When potassium is reacted with water which compound(s) is are formed preferentially?

  • K2O

  • KO2

  • Both K2O and KO2

  • K2O2


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23.

Select the most appropriate statement In BF3.

  • All the bonds are completely ionic.

  • All the bonds are covalent.

  • The B-F bond is partially ionic.

  • B-F bond has partial double bond character.


B.

All the bonds are covalent.

BF3 is a covalent compound. Boron or B has 3 valency electrons with number d-orbital whereas Fluorine or F has 7 valency electrons with number d-orbital.

Thus, it will form 3 covalent bonds with 3 fluorine atoms to complete its octate and give a stable BF3 compound.

Therefore, BF3 is a covalent compound.


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24.

When MnO2 is fused with KOH and KNO2 , a coloured compound is formed. Choose the right compound with the appropriate colour.

  • K2MnO4, green

  • KMnO4, purple

  • Mn2O3, brown

  • Mn3O4, black


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25.

Identify the case(s) where there is change is oxidation number

  • Acidified solution of CrO42-

  • SO2 gas bubbled through an acidic solution Cr2O72-

  • Alkaline solution of CrO72-

  • Ammoniacal solution of CrO42-


26.

The solution which does not produce precipitate when treated with aqueous K2CO3 is

  • BaCl2

  • CaBr2

  • MgCl2

  • Na2SO4


27.

Lassaigne's test (with silver nitrate) is commonly used to detect halogens such as chlorine, bromine and iodine but not useful to detect fluorine because the product AgF formed is

  • Volatile

  • Reactive

  • Explosive

  • Soluble in water


28.

The reaction in propene with HBr is presence of peroxide proceeds through the intermediate

  • H3C - C.H - CH3

  • H3C - C.H -CH2Br

  • H3C - CH|Br - C.H2

  • H3C - CH2C.H2


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29.

Cycloheptatrienyl cation is

  • Non-benzenoid and non-aromatic

  • Non-benzenoid and aromatic

  • Benzenoid and non-aromatic

  • Benzenoid and aromatic


30.

Which of the following is not true about a catalyst?

  • Mechanism of the reaction in presence and absence of catalyst could be different.

  • Use of catalyst cannot change the order of the reaction

  • Catalyst enhances both forward and backwards reaction at equal rate.

  • Catalyst participates in the reaction, but not consumed in the process.


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