Chemistry

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Showing 926 to 950 of 1398 questions (page 38 of 56).

926. Decantation is suitable when the precipitate is

A. gaseous B. volatile C. heavy and settles quickly D. very fine and colloidal E. soluble in the solvent

927. In column chromatography, the component that is most strongly adsorbed on the stationary phase

A. travels slowest and is eluted last B. does not move at all C. travels fastest D. changes colour E. dissolves the column

928. In a mixture of 2 mol of nitrogen and 3 mol of oxygen, the mole fraction of oxygen is

A. 0.2 B. 1.5 C. 0.5 D. 0.4 E. 0.6

929. If the mole fraction of oxygen in a gas mixture at 2 atm total pressure is 0.25, its partial pressure is

A. 8 atm B. 0.5 atm C. 1 atm D. 0.25 atm E. 2 atm

930. Which gas would be expected to show the greatest deviation from ideal behaviour?

A. hydrogen B. ammonia C. helium D. neon E. nitrogen

931. The difference between evaporation and boiling is that boiling

A. occurs throughout the liquid at a fixed temperature B. lowers the temperature C. occurs only at the surface D. requires no heat E. occurs at all temperatures

932. The number of atoms per unit cell in a simple cubic lattice is

A. 8 B. 4 C. 6 D. 1 E. 2

933. Lattice energy of an ionic compound increases with

A. decreasing charges B. increasing coordination number only C. increasing ionic charges and decreasing ionic radii D. increasing temperature E. increasing ionic radii

934. Hydrogen fluoride exists in the liquid state as zig zag chains because of

A. London forces only B. hydrogen bonding between molecules C. covalent network bonding D. metallic bonding E. ionic bonding

935. Orbitals of the same subshell that have equal energy in an isolated atom are described as

A. degenerate B. antibonding C. saturated D. polar E. hybrid

936. The dual nature of matter was proposed by

A. de Broglie B. Chadwick C. Dalton D. Rutherford E. Bohr

937. The bond angle in boron trifluoride is

A. 90 degrees B. 104.5 degrees C. 120 degrees D. 180 degrees E. 109.5 degrees

938. The sulphur dioxide molecule is

A. tetrahedral B. trigonal planar C. square planar D. linear E. bent

939. A molecule may contain polar bonds and still have no net dipole moment if it is

A. paramagnetic B. symmetrical so that the bond dipoles cancel C. hydrogen bonded D. ionic E. linear only

940. The number of sigma bonds in a methane molecule is

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

941. On an enthalpy level diagram for an exothermic reaction, the products lie

A. above the activated complex B. at zero enthalpy C. below the reactants D. at the same level as the reactants E. above the reactants

942. Raising the temperature of 100 g of water by 10 K requires about

A. 41.8 J B. 418 J C. 4180 J D. 10 J E. 41800 J

943. An aqueous solution of ammonium chloride is

A. neutral B. acidic C. basic D. amphoteric E. a buffer of pH 7

944. For the reaction in which one mole of gas gives two moles of gas, an increase in volume at constant temperature

A. shifts the equilibrium to the right B. stops the reaction C. has no effect D. shifts the equilibrium to the left E. decreases Kc

945. In an acid base titration, the point at which the amounts of acid and base are chemically equivalent is the

A. neutral point of water B. buffer region C. end point of the indicator only D. equivalence point E. isoelectric point

946. Diluting 10 cm3 of a 2 mol dm-3 solution to a total volume of 100 cm3 gives a concentration of

A. 2 mol dm-3 B. 20 mol dm-3 C. 0.2 mol dm-3 D. 0.02 mol dm-3 E. 0.5 mol dm-3

947. The mole fraction of the solute in a solution of 1 mol of solute in 9 mol of solvent is

A. 1.0 B. 0.09 C. 0.9 D. 0.11 E. 0.1

948. A concentration expressed as percentage weight by volume means grams of solute per

A. mole of solvent B. 100 cm3 of solution C. 100 g of solution D. 1 dm3 of solvent E. 1 kg of solvent

949. The products of the electrolysis of molten sodium chloride are

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

950. The oxidation number of chromium in the chromate ion is

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

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