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Showing 1126 to 1150 of 3046 questions (page 46 of 122).

1126. A nickel cadmium cell is an example of

A. a fuel cell B. a concentration cell C. an electrolytic cell only D. a secondary cell E. a primary cell

1127. A hydrogen oxygen fuel cell differs from an ordinary cell in that it

A. is supplied with reactants continuously from outside B. operates without electrodes C. stores its reactants internally D. produces no water E. cannot be recharged and so is useless

1128. The unit of the rate constant for a first order reaction is

A. mol dm-3 s-1 B. dm3 mol-1 s-1 C. dimensionless D. dm6 mol-2 s-1 E. s-1

1129. In a multistep reaction, the overall rate is governed by the

A. fastest step B. first step always C. slowest step D. step with the most reactants E. last step always

1130. A rise in temperature of about 10 K commonly

A. halves the reaction rate B. roughly doubles the reaction rate C. changes the order of the reaction D. has no effect on the rate E. lowers the activation energy

1131. The decomposition of hydrogen peroxide by manganese dioxide is an example of

A. heterogeneous catalysis B. negative catalysis C. enzyme catalysis D. autocatalysis E. homogeneous catalysis

1132. A substance that decreases the rate of a reaction is called

A. a catalyst poison for enzymes only B. an activator C. a promoter D. a co-factor E. an inhibitor

1133. The element with the highest electronegativity is

A. oxygen B. chlorine C. nitrogen D. fluorine E. caesium

1134. Metallic character generally

A. is highest for noble gases B. increases down a group C. increases across a period D. is unrelated to position E. decreases down a group

1135. The screening or shielding effect of inner electrons

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

1136. The number of elements in the fourth period of the periodic table is

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

1137. Alkali metals are stored under kerosene oil because they

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

1138. Among the alkali metals, lithium has the highest

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

1139. The chemical formula of gypsum is

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

1140. Sodium carbonate is used industrially mainly in the manufacture of

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

1141. Carbon monoxide is highly toxic because it

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

1142. The catalyst used in the contact process for manufacturing sulphuric acid is

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

1143. Silicon carbide is used as an abrasive because it is

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

1144. Concentrated nitric acid acts on copper mainly as

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

1145. The bleaching action of chlorine water is due to

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

1146. The oxidation state of chromium in the dichromate ion is

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

1147. 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

1148. Stainless steel is an alloy of iron with

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

1149. In acidic medium, permanganate ion is reduced to

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

1150. Successive members of a homologous series differ by

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

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