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Showing 651 to 675 of 3046 questions (page 27 of 122).

651. An aqueous solution of sodium acetate is

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

652. The solubility product expression for silver chloride is

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

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

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

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

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

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

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

656. The solubility of most gases in water

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

657. An oxidizing agent is a species that

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

658. The oxidation number of sulphur in sulphuric acid is

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

659. The standard cell potential is calculated as

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

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

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

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

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

662. A nickel cadmium cell is an example of

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

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

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

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

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

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

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

666. A rise in temperature of about 10 K commonly

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

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

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

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

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

669. The element with the highest electronegativity is

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

670. Metallic character generally

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

671. The screening or shielding effect of inner electrons

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

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

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

673. Alkali metals are stored under kerosene oil because they

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

674. Among the alkali metals, lithium has the highest

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

675. The chemical formula of gypsum is

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

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