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Showing 1776 to 1800 of 3046 questions (page 72 of 122).

1776. The number of elements in the fourth period of the periodic table is

A. 2 B. 32 C. 8 D. 10 E. 18

1777. Alkali metals are stored under kerosene oil because they

A. dissolve in water slowly B. are volatile C. react vigorously with air and moisture D. sublime readily E. are radioactive

1778. Among the alkali metals, lithium has the highest

A. atomic radius B. density C. ionization energy D. atomic number E. reactivity with water

1779. The chemical formula of gypsum is

A. CaSO4.2H2O B. CaCO3 C. CaSO4 D. CaSO4.(1/2)H2O E. CaO

1780. Sodium carbonate is used industrially mainly in the manufacture of

A. fertilizer B. plastics C. cement D. glass E. petrol

1781. Carbon monoxide is highly toxic because it

A. is acidic B. dissolves in water C. decomposes in the lungs D. reacts with nitrogen E. binds strongly to haemoglobin in place of oxygen

1782. The catalyst used in the contact process for manufacturing sulphuric acid is

A. nickel B. aluminium chloride C. platinum D. iron E. vanadium pentoxide

1783. 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

1784. 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

1785. 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

1786. The oxidation state of chromium in the dichromate ion is

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

1787. 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

1788. 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

1789. In acidic medium, permanganate ion is reduced to

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

1790. Successive members of a homologous series differ by

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

1791. The number of structural isomers of butane, C4H10, is

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

1792. 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

1793. Dehydration of ethanol with concentrated sulphuric acid gives

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

1794. 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

1795. 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

1796. 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

1797. 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

1798. Vigorous oxidation of toluene with alkaline potassium permanganate gives

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

1799. 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

1800. 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

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