Chemistry

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Showing 901 to 925 of 1398 questions (page 37 of 56).

901. An electrophile is a species that

A. donates a proton only B. accepts an electron pair C. contains a lone pair always D. donates an electron pair E. is always negatively charged

902. The order of stability of carbocations is

A. primary greater than secondary greater than tertiary B. all equal C. secondary greater than tertiary greater than primary D. primary greater than tertiary E. tertiary greater than secondary greater than primary

903. Polythene is obtained from ethene by

A. addition polymerization B. elimination C. condensation polymerization D. substitution E. oxidation

904. Hydrogenation of vegetable oils to make vanaspati ghee uses a catalyst of

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

905. The catalyst used for the chlorination of benzene is

A. platinum B. anhydrous ferric chloride C. sodium hydroxide D. nickel E. vanadium pentoxide

906. The order of reactivity of alkyl halides towards nucleophilic substitution is

A. R-Br greater than R-F greater than R-I B. R-Cl greater than R-I C. all equal D. R-I greater than R-Br greater than R-Cl greater than R-F E. R-F greater than R-Cl greater than R-Br greater than R-I

907. Industrial ethanol is produced by the fermentation of

A. fats B. nitrogen compounds C. proteins D. cellulose directly E. sugars by yeast

908. Denatured alcohol is ethanol that has been made unfit for drinking by adding

A. sugar B. methanol and other additives C. water D. glycerol E. salt

909. Glycerol is classified as

A. a monohydric alcohol B. an ether C. a phenol D. a trihydric alcohol E. a dihydric alcohol

910. Diethyl ether was formerly used as

A. a fertilizer B. a fuel additive C. a general anaesthetic D. a preservative for food E. a bleaching agent

911. Aldehydes and ketones characteristically undergo

A. nucleophilic addition at the carbonyl carbon B. polymerization only C. electrophilic substitution D. free radical substitution E. elimination

912. Heating a carboxylic acid with ammonia gives, after loss of water,

A. an anhydride B. an amine C. an ester D. an amide E. a nitrile

913. The general formula of a naturally occurring alpha amino acid is

A. RCH(NH2)COOH B. RCH2CONH2 C. RCOOR D. RCHO E. RCH(OH)COOH

914. Denaturation of a protein involves

A. addition of amino acids B. hydrogenation C. polymerization D. breaking of peptide bonds E. loss of the three dimensional structure without breaking peptide bonds

915. Starch gives a characteristic colour with iodine solution that is

A. red B. yellow C. blue black D. colourless E. green

916. Detergents work better than soaps in hard water because their calcium and magnesium salts are

A. soluble B. volatile C. acidic D. insoluble E. coloured

917. Urea is manufactured by reacting ammonia with

A. nitrogen B. sulphur dioxide C. carbon dioxide D. carbon monoxide E. water

918. Eutrophication of a lake is caused mainly by

A. low temperature B. excess chlorine C. acid rain alone D. excess nutrients such as nitrates and phosphates E. high dissolved oxygen

919. Dissolved oxygen in a river falls when organic pollution rises because

A. the temperature falls B. the pollutant displaces the oxygen physically C. the water becomes acidic D. oxygen reacts with the pollutant directly only E. micro-organisms consume oxygen while decomposing the organic matter

920. Infrared spectroscopy is used chiefly to identify

A. optical activity B. functional groups C. molar mass D. crystal structure E. isotopes

921. If 5 g of a product is obtained where 8 g was theoretically possible, the percentage yield is

A. 37.5% B. 80% C. 160% D. 50% E. 62.5%

922. A gram atom of an element is

A. the mass of one molecule B. one atom of the element C. its atomic number in grams D. always 12 g E. the mass in grams numerically equal to its relative atomic mass

923. A mass spectrometer separates and detects ions after they have been

A. cooled and condensed B. ionized, accelerated and deflected C. dissolved in water D. precipitated E. burnt in oxygen

924. In the reaction of nitrogen with hydrogen to form ammonia, 1 mol of nitrogen reacting completely gives ammonia of amount

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

925. Fractional crystallization is used to separate

A. two solids of different solubilities from the same solution B. two gases C. a solid from a gas D. two immiscible liquids E. isotopes

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