Chemistry

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Showing 1126 to 1150 of 1398 questions (page 46 of 56).

1126. Internal energy is a state function, which means it depends on

A. the container shape B. only the initial and final states C. the time taken D. the catalyst used E. the path taken

1127. A reversible reaction never goes to completion because

A. the catalyst is exhausted B. the pressure drops C. the reverse reaction becomes appreciable as products accumulate D. the temperature falls E. the reactants are impure

1128. Raising the temperature of an exothermic reaction at equilibrium

A. stops the reaction B. shifts it towards the products C. increases Kc D. has no effect E. shifts it towards the reactants

1129. The pH of pure water at 25 degrees Celsius is

B. 14 C. 6 D. 7 E. 8

1130. A larger value of the acid dissociation constant Ka indicates

A. a neutral solution B. a buffer solution C. a stronger acid D. a weaker acid E. a stronger base

1131. An aqueous solution of sodium acetate is

A. acidic B. basic C. a buffer on its own only at pH 7 D. amphoteric E. neutral

1132. The solubility product expression for silver chloride is

A. [Ag+][Cl-] B. [AgCl]/[Ag+][Cl-] C. [Ag+]/[Cl-] D. [Ag+]2[Cl-] E. [Ag+][Cl-]2

1133. Dissolving 0.5 mol of solute in enough water to make 250 cm3 of solution gives a molarity of

A. 0.5 M B. 0.125 M C. 1 M D. 2 M E. 5 M

1134. The osmotic pressure of a dilute solution is given by

A. pi V = n/RT B. pi V = nRT C. pi = nRTV D. pi = n/V E. pi = RT/nV

1135. Molarity changes with temperature but molality does not, because molarity depends on

A. the volume of solution B. the number of moles of solute C. the nature of the solute D. the mass of solute E. the mass of solvent

1136. The solubility of most gases in water

A. increases with decreasing pressure B. is independent of temperature C. decreases with temperature D. is unaffected by pressure E. increases with temperature

1137. An oxidizing agent is a species that

A. donates protons B. gains electrons C. increases its own oxidation number D. always contains oxygen E. loses electrons

1138. The oxidation number of sulphur in sulphuric acid is

B. +2 C. +4 D. -2 E. +6

1139. The standard cell potential is calculated as

A. always zero B. the average of the two potentials C. anode potential minus cathode potential D. cathode potential minus anode potential E. the sum of the two reduction potentials

1140. The products of the electrolysis of concentrated aqueous sodium chloride using inert electrodes are

A. oxygen and hydrogen only B. sodium and oxygen C. hydrogen, chlorine and sodium hydroxide D. sodium and chlorine E. chlorine and oxygen only

1141. The function of the salt bridge in a galvanic cell is to

A. increase the cell voltage B. maintain electrical neutrality in the two half cells C. prevent oxidation D. supply electrons to the circuit E. act as the cathode

1142. A nickel cadmium cell is an example of

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

1143. 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. produces no water D. cannot be recharged and so is useless E. stores its reactants internally

1144. The unit of the rate constant for a first order reaction is

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

1145. In a multistep reaction, the overall rate is governed by the

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

1146. A rise in temperature of about 10 K commonly

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

1147. The decomposition of hydrogen peroxide by manganese dioxide is an example of

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

1148. A substance that decreases the rate of a reaction is called

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

1149. The element with the highest electronegativity is

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

1150. Metallic character generally

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

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