Chemistry

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Showing 801 to 825 of 1398 questions (page 33 of 56).

801. Silicon carbide is used as an abrasive because it is

A. highly ionic B. metallic C. a covalent network solid of great hardness D. volatile E. a soft molecular solid

802. Concentrated nitric acid acts on copper mainly as

A. a dehydrating agent B. a reducing agent C. a catalyst D. an oxidizing agent E. a base

803. The bleaching action of chlorine water is due to

A. hydrogen gas B. reduction of the dye C. chlorine gas dissolving the dye D. hydrochloric acid E. nascent oxygen from hypochlorous acid

804. The oxidation state of chromium in the dichromate ion is

A. +6 B. +2 C. +7 D. +4 E. +3

805. Paramagnetism in transition metal compounds is due to

A. the nucleus B. delocalized pi bonds C. lattice vibrations D. unpaired d electrons E. paired electrons

806. Stainless steel is an alloy of iron with

A. aluminium and silicon B. lead and zinc C. chromium and nickel D. copper and tin E. carbon only

807. In acidic medium, permanganate ion is reduced to

A. Mn3+ B. Mn2+ C. MnO4 2- D. Mn metal E. MnO2

808. Successive members of a homologous series differ by

A. CH3 B. CH4 C. H2 D. C2H4 E. CH2

809. The number of structural isomers of butane, C4H10, is

A. 2 B. 5 C. 3 D. 4 E. 1

810. The Wurtz reaction is used to prepare

A. ketones from acids B. symmetrical alkanes from alkyl halides C. alkenes from alcohols D. alcohols from esters E. alkynes from dihalides

811. Dehydration of ethanol with concentrated sulphuric acid gives

A. ethane B. ethanoic acid C. ethene D. ethyne E. ethanal

812. Baeyer's reagent, dilute alkaline potassium permanganate, is used to test for

A. alcohols B. carboxylic acids C. unsaturation in hydrocarbons D. aldehydes E. amines

813. Ethyne is prepared in the laboratory by the action of water on

A. calcium carbonate B. calcium chloride C. calcium sulphate D. calcium carbide E. calcium oxide

814. The catalyst used in Friedel Crafts alkylation of benzene is

A. concentrated sulphuric acid B. nickel C. sodium hydroxide D. vanadium pentoxide E. anhydrous aluminium chloride

815. The nitrating mixture used for the nitration of benzene consists of

A. ammonium nitrate and water B. concentrated nitric and concentrated sulphuric acids C. dilute nitric acid alone D. nitrous acid and ethanol E. nitric acid and sodium hydroxide

816. Vigorous oxidation of toluene with alkaline potassium permanganate gives

A. benzene B. benzaldehyde C. cyclohexanol D. benzoic acid E. phenol

817. A tertiary alkyl halide undergoes nucleophilic substitution mainly by

A. addition B. E2 elimination only C. the SN1 mechanism D. the SN2 mechanism E. free radical substitution

818. Treatment of an alkyl halide with alcoholic potassium hydroxide gives mainly

A. an amine B. an ether C. an acid D. an alcohol E. an alkene

819. Reaction of an alkyl halide with potassium cyanide gives a

A. ketone B. nitrile C. amine D. alcohol E. carboxylic acid directly

820. Lucas reagent is used to distinguish between

A. primary, secondary and tertiary alcohols B. acids and esters C. alkanes and alkenes D. amines and amides E. aldehydes and ketones

821. Williamson synthesis is used to prepare

A. amines B. alcohols C. aldehydes D. ethers E. esters

822. Formalin is an aqueous solution containing about 40 per cent

A. formaldehyde B. acetaldehyde C. acetone D. ethanol E. formic acid

823. Fehling's solution is reduced by aldehydes to give a precipitate of

A. copper metal B. copper(II) hydroxide C. silver D. cuprous chloride E. copper(I) oxide

824. Reduction of a ketone with sodium borohydride gives

A. an alkane B. a secondary alcohol C. an aldehyde D. a primary alcohol E. a tertiary alcohol

825. Soap is manufactured by the alkaline hydrolysis of fats, a process called

A. polymerization B. cracking C. esterification D. saponification E. hydrogenation

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