A white solid 'A' on heating gives off a gas which turns lime wat

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 Multiple Choice QuestionsMultiple Choice Questions

291.

The reactivity of the alkali metal sodium with water, is made use of

  • in drying of alcohols

  • in drying of benzene

  • in drying of organic amines

  • as a general drying agent


292.

The bleaching action of the bleaching powder is due to the liberation of

  • chlorine

  • molecular oxygen

  • nascent oxygen

  • calcium carbonate


293.

Calcium carbide reacts with water to produce

  • methane

  • ethane

  • ethylene

  • acetylene


294.

Heating together of sodium ethoxide and ethyl iodide wll give

  • ether

  • ethyl alcohol

  • acetaldehyde

  • acetic acid


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295.

TEL is

  • a petrol fuel

  • anti-knocking compound

  • Gasoline

  • insecticide


296.

The colour of K2Cr2O7 in acidic medium is

  • red

  • green

  • yellow

  • pink


297.

Formula of washing soda is

  • Na2CO3.10H2O

  • Na2CO3

  • Na2SO4.10H2O

  • None of the above


298.

Which one of the following is an s-block element?

  • Aluminium

  • Chromium

  • Niobium

  • Potassium


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299.

The alkali metal that reacts with nitrogen directly to form nitride is

  • Li

  • Na

  • K

  • Rb


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300.

A white solid 'A' on heating gives off a gas which turns lime water milky. The residue is yellow when hot but turns white on cooling. This solid 'A' is

  • zinc sulphate

  • zinc carbonate

  • lead sulphate

  • lead carbonate


B.

zinc carbonate

Solid (A) on heating gives off a gas which turns lime water milky it means the gas is carbon dioxide. ZnO becomes yellow when hot, white when cold.

ZnCO3  ZnO + CO2 

Note : Zinc sulphate on heating doesn't show yellow colour.

 


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