Chemistry

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Showing 1151 to 1175 of 1398 questions (page 47 of 56).

1151. The screening or shielding effect of inner electrons

A. decreases the effective nuclear charge felt by outer electrons B. has no effect on atomic size C. increases ionization energy D. only applies to d electrons E. increases the effective nuclear charge

1152. The number of elements in the fourth period of the periodic table is

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

1153. Alkali metals are stored under kerosene oil because they

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

1154. Among the alkali metals, lithium has the highest

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

1155. The chemical formula of gypsum is

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

1156. Sodium carbonate is used industrially mainly in the manufacture of

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

1157. Carbon monoxide is highly toxic because it

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

1158. The catalyst used in the contact process for manufacturing sulphuric acid is

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

1159. Silicon carbide is used as an abrasive because it is

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

1160. Concentrated nitric acid acts on copper mainly as

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

1161. The bleaching action of chlorine water is due to

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

1162. The oxidation state of chromium in the dichromate ion is

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

1163. Paramagnetism in transition metal compounds is due to

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

1164. Stainless steel is an alloy of iron with

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

1165. In acidic medium, permanganate ion is reduced to

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

1166. Successive members of a homologous series differ by

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

1167. The number of structural isomers of butane, C4H10, is

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

1168. The Wurtz reaction is used to prepare

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

1169. Dehydration of ethanol with concentrated sulphuric acid gives

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

1170. Baeyer's reagent, dilute alkaline potassium permanganate, is used to test for

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

1171. Ethyne is prepared in the laboratory by the action of water on

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

1172. The catalyst used in Friedel Crafts alkylation of benzene is

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

1173. The nitrating mixture used for the nitration of benzene consists of

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

1174. Vigorous oxidation of toluene with alkaline potassium permanganate gives

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

1175. A tertiary alkyl halide undergoes nucleophilic substitution mainly by

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

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