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Chemistry

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Showing 526 to 550 of 1398 questions (page 22 of 56).

526. Fehling's solution is reduced by aldehydes to give a precipitate of

A. copper metal B. cuprous chloride C. copper(II) hydroxide D. silver E. copper(I) oxide

527. Reduction of a ketone with sodium borohydride gives

A. an alkane B. a secondary alcohol C. a tertiary alcohol D. an aldehyde E. a primary alcohol

528. Soap is manufactured by the alkaline hydrolysis of fats, a process called

A. polymerization B. hydrogenation C. esterification D. saponification E. cracking

529. Aspirin is chemically

A. salicylic acid B. acetylsalicylic acid C. methyl salicylate D. benzoic acid E. phenol

530. The monomer of polyvinyl chloride is

A. propene B. styrene C. vinyl chloride D. chloroform E. ethene

531. Vulcanization of rubber involves heating it with

A. sulphur B. nitrogen C. carbon D. phosphorus E. chlorine

532. The building blocks of nucleic acids are

A. fatty acids B. nucleotides C. amino acids D. glycerols E. monosaccharides

533. Vitamins B and C are described as water soluble because they

A. contain long hydrocarbon chains B. are minerals C. contain several polar hydroxyl and amino groups D. are stored in fat tissue E. are proteins

534. The specificity of an enzyme is explained by the

A. resonance theory B. band theory C. collision theory D. lock and key model of the active site E. kinetic theory

535. Cracking of heavy petroleum fractions is carried out to

A. form aromatics only B. remove sulphur only C. increase the boiling point D. increase the molar mass E. obtain lighter and more useful hydrocarbons

536. The octane number of a fuel measures its

A. resistance to knocking B. volatility C. sulphur content D. energy content E. density

537. Biochemical oxygen demand is a measure of

A. the total dissolved solids B. the hardness of water C. the oxygen required by micro-organisms to decompose organic matter in water D. the acidity of water E. the chlorine content

538. Primary treatment of waste water consists mainly of

A. ion exchange B. chlorination C. reverse osmosis D. physical removal of suspended solids by screening and sedimentation E. biological oxidation

539. Photochemical smog is formed mainly from

A. nitrogen oxides and unburnt hydrocarbons in sunlight B. sulphur dioxide and soot C. ammonia and dust D. carbon dioxide and water E. chlorofluorocarbons

540. Two components can be separated by chromatography because they differ in

A. molar mass only B. density C. their relative affinity for the stationary and mobile phases D. colour E. melting point

541. Avogadro's law states that equal volumes of all gases under the same conditions contain

A. equal numbers of atoms B. the same density C. the same energy D. equal numbers of molecules E. equal masses

542. The number of moles present in 4.4 g of carbon dioxide is

A. 0.01 B. 0.2 C. 0.44 D. 1.0 E. 0.1

543. The percentage of oxygen by mass in water is about

A. 11.1% B. 88.9% C. 50% D. 66.7% E. 33.3%

544. The complete combustion of one mole of methane requires oxygen of amount

A. 1 mol B. 2 mol C. 3 mol D. 1.5 mol E. 0.5 mol

545. For solvent extraction to work, the two solvents used must be

A. of the same density B. both aqueous C. immiscible with each other D. miscible with each other E. chemically identical

546. A Buchner funnel with a filter flask is used for

A. titration B. distillation C. crystallization D. sublimation E. filtration under suction

547. The solution left after crystals have separated out during crystallization is called the

A. mother liquor B. supernatant gas C. distillate D. eluent E. filtrate only

548. In thin layer chromatography, the stationary phase is supported on

A. a strip of paper B. a metal wire C. a glass or plastic plate D. a filter funnel E. a column of solvent

549. A gas occupies 2 dm3 at 1 atm. At constant temperature and 4 atm its volume becomes

A. 4 dm3 B. 1 dm3 C. 8 dm3 D. 0.5 dm3 E. 2 dm3

550. A gas occupying 273 cm3 at 273 K is heated at constant pressure to 546 K. Its new volume is

A. 409 cm3 B. 273 cm3 C. 136 cm3 D. 1092 cm3 E. 546 cm3

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