Chemistry

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Showing 101 to 125 of 1398 questions (page 5 of 56).

101. Tollen's reagent is used to distinguish

A. alcohols from ethers B. aldehydes from ketones C. acids from esters D. alkanes from alkenes E. amines from amides

102. Carboxylic acids are more acidic than alcohols because

A. they have a longer chain B. the carboxylate ion is resonance stabilized C. they are less soluble D. they contain two oxygen atoms of equal bond length only in the acid E. they are liquids

103. The reaction of a carboxylic acid with an alcohol in the presence of an acid catalyst is called

A. saponification B. esterification C. hydrolysis D. decarboxylation E. nitration

104. At its isoelectric point, an amino acid exists mainly as

A. a cation B. an anion C. a zwitterion D. a neutral unionized molecule E. a free radical

105. The linkage joining amino acid residues in a protein is

A. a glycosidic bond B. a peptide bond C. an ester linkage D. a disulphide bond only E. an ionic bond

106. Nylon 6,6 is an example of

A. an addition polymer B. a condensation polymer C. a natural polymer D. an elastomer formed by vulcanization E. a silicone

107. Which of the following is a reducing sugar?

A. sucrose B. glucose C. starch D. cellulose E. glycogen

108. The percentage of nitrogen in urea is about

A. 21% B. 35% C. 46% D. 60% E. 82%

109. Depletion of stratospheric ozone is mainly caused by

A. carbon dioxide B. chlorofluorocarbons C. sulphur dioxide D. methane E. nitrogen gas

110. Acid rain is caused mainly by the oxides of

A. carbon and hydrogen B. sulphur and nitrogen C. sodium and potassium D. iron and copper E. silicon and boron

111. The chief greenhouse gas responsible for the enhanced greenhouse effect is

A. oxygen B. nitrogen C. carbon dioxide D. argon E. helium

112. The stationary phase in thin layer chromatography is usually

A. silica gel or alumina B. the mobile solvent C. air D. water only E. the sample itself

113. The value of Avogadro's number is

A. 6.02 x 10^22 B. 6.02 x 10^23 C. 6.02 x 10^24 D. 3.01 x 10^23 E. 1.66 x 10^-24

114. The molar volume of an ideal gas at standard temperature and pressure is

A. 11.2 dm3 B. 22.414 dm3 C. 24 dm3 D. 1 dm3 E. 44.8 dm3

115. The reactant that is completely consumed first and therefore limits the amount of product is called the

A. excess reactant B. limiting reactant C. catalyst D. intermediate E. spectator species

116. A compound contains 40% carbon, 6.7% hydrogen and 53.3% oxygen by mass. Its empirical formula is

A. CHO B. CH2O C. C2H4O2 D. CH4O E. C2H6O

117. The number of moles in 9.8 g of sulphuric acid is

A. 0.05 B. 0.1 C. 0.2 D. 1.0 E. 0.98

118. The number of molecules in 11.2 dm3 of oxygen gas at STP is

A. 6.02 x 10^23 B. 3.01 x 10^23 C. 1.204 x 10^24 D. 6.02 x 10^22 E. 1.5 x 10^23

119. Isotopes of an element are separated on the basis of

A. chemical reactivity B. difference in mass C. difference in colour D. difference in charge only E. boiling point of the compound

120. A fluted filter paper is used in filtration to

A. reduce the pore size B. increase the surface area available for filtration C. remove coloured impurities D. dry the precipitate E. neutralize the filtrate

121. Which pair of substances can be purified by sublimation?

A. sodium chloride and sugar B. iodine and naphthalene C. glucose and urea D. copper sulphate and alum E. ethanol and water

122. In paper chromatography, the Rf value of a component is always

A. greater than 1 B. equal to 1 C. less than or equal to 1 D. negative E. independent of the solvent

123. Solvent extraction is governed by the

A. law of mass action B. distribution law C. law of definite proportions D. Hess's law E. Raoult's law

124. A good solvent for crystallization should

A. dissolve the solute equally well hot and cold B. dissolve the solute more when hot than when cold C. react with the solute D. have a very high boiling point only E. dissolve the impurities only when cold

125. Boyle's law states that at constant temperature the volume of a given mass of gas is

A. directly proportional to pressure B. inversely proportional to pressure C. independent of pressure D. proportional to the square of pressure E. proportional to temperature

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