Mixed Practice

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Showing 2726 to 2750 of 3046 questions (page 110 of 122).

2726. Dissolving 0.5 mol of a solute in 500 g of solvent gives a molality of

A. 0.5 m B. 0.25 m C. 5 m D. 2 m E. 1 m

2727. The mass of sodium hydroxide required to prepare 1 dm3 of a 0.5 mol dm-3 solution is

A. 10 g B. 80 g C. 20 g D. 5 g E. 40 g

2728. Colligative properties are used experimentally to determine the

A. boiling point of the solvent only B. colour of a solute C. molar mass of a solute D. viscosity of the solution E. density of the solvent

2729. A cell placed in a hypertonic solution will

A. shrink as water leaves it B. divide C. swell and burst D. remain unchanged E. gain solute rapidly

2730. Rusting of iron requires the presence of

A. nitrogen B. both oxygen and water C. water only D. oxygen only E. carbon dioxide only

2731. Galvanizing protects iron because zinc

A. is less reactive than iron B. forms an ionic bond with iron C. is a better conductor D. prevents the entry of nitrogen only E. is more reactive and corrodes preferentially as a sacrificial metal

2732. During electroplating, the article to be plated is made the

A. cathode B. electrolyte C. reference electrode D. salt bridge E. anode

2733. According to Faraday's first law, the mass of a substance deposited during electrolysis is proportional to

A. the voltage applied B. the temperature C. the electrode area D. the quantity of charge passed E. the resistance of the cell

2734. The standard reduction potential of the zinc electrode is about

A. 0.00 V B. -0.34 V C. +0.76 V D. +0.34 V E. -0.76 V

2735. The usual unit of reaction rate is

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

2736. According to collision theory, a collision leads to reaction only if the molecules have sufficient energy and

A. identical speeds B. equal masses C. a catalyst present D. the same charge E. the correct orientation

2737. A reaction initiated by the absorption of light is called

A. an electrochemical reaction B. an autocatalytic reaction C. a photochemical reaction D. a thermal reaction E. a chain terminating reaction

2738. For a main group element, the number of valence electrons is indicated by its

A. atomic radius B. period number C. group number D. oxidation state only E. atomic mass

2739. The second ionization energy of an element is always greater than the first because

A. the electron is closer to the nucleus in the neutral atom B. shielding increases C. the nuclear charge decreases D. the atom becomes larger E. an electron is removed from a positively charged ion

2740. Across a period, the character of the oxides changes from

A. acidic through amphoteric to basic B. basic to neutral only C. unchanged D. basic through amphoteric to acidic E. acidic to neutral only

2741. The transition elements occupy the

A. f block B. d block C. noble gas group D. s block E. p block

2742. The chemical inertness of the noble gases is due to their

A. completely filled valence shells B. low atomic mass C. high density D. large size E. radioactivity

2743. The hydrides of the alkali metals are

A. polymeric B. ionic solids containing the hydride ion C. non-existent D. metallic E. covalent and volatile

2744. Permanent hardness of water is caused mainly by dissolved

A. calcium and magnesium sulphates and chlorides B. potassium nitrate C. dissolved carbon dioxide D. sodium chloride E. calcium and magnesium bicarbonates

2745. Caustic soda is the common name for

A. sodium bicarbonate B. sodium carbonate C. calcium hydroxide D. sodium hydroxide E. sodium chloride

2746. Graphite conducts electricity because

A. it contains free protons B. it is amorphous C. each carbon has one delocalized electron in a layer structure D. its atoms are sp3 hybridized E. it has ionic bonds

2747. Ammonia is manufactured industrially by the

A. Ostwald process B. Haber process C. contact process D. Bosch process E. Solvay process

2748. Sulphur dioxide acts as a bleaching agent by

A. reduction B. adsorption only C. hydrolysis D. precipitation E. oxidation

2749. Anhydrous copper sulphate is white while the pentahydrate is blue because the colour arises from

A. water molecules coordinated to the copper ion B. impurities C. hydrogen bonding alone D. the crystal shape E. the sulphate ion

2750. The catalyst used in a vehicle catalytic converter is mainly

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

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