Chemistry

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Showing 201 to 225 of 1398 questions (page 9 of 56).

201. The colour of most transition metal ions in solution is due to

A. s to p transitions B. d to d electronic transitions C. nuclear transitions D. hydrogen bonding E. ionic size

202. In the complex ion hexaamminecobalt(III), the coordination number of cobalt is

A. 3 B. 4 C. 5 D. 6 E. 2

203. EDTA is an example of a

A. monodentate ligand B. bidentate ligand C. hexadentate chelating ligand D. neutral molecule that cannot coordinate E. cation

204. Transition metals show variable oxidation states because

A. their atomic radii are large B. the energies of the ns and (n-1)d electrons are close C. they are all diamagnetic D. they form only ionic compounds E. their ionization energies are very high

205. The hybridization of each carbon atom in ethene is

A. sp B. sp2 C. sp3 D. sp3d E. sp3d2

206. The halogenation of alkanes in sunlight proceeds by a

A. nucleophilic substitution mechanism B. electrophilic addition mechanism C. free radical substitution mechanism D. elimination mechanism E. rearrangement

207. According to Markownikoff's rule, addition of hydrogen bromide to propene gives mainly

A. 1-bromopropane B. 2-bromopropane C. 1,2-dibromopropane D. propan-1-ol E. propane

208. Benzene characteristically undergoes

A. electrophilic addition B. electrophilic substitution C. nucleophilic addition D. free radical addition E. elimination

209. A primary alkyl halide reacting with a strong nucleophile typically follows

A. the SN1 mechanism B. the SN2 mechanism C. free radical substitution D. E1 elimination E. electrophilic addition

210. A Grignard reagent has the general formula

A. RMgX B. RLiX C. RNaX D. RZnX E. RAlX

211. Controlled oxidation of a primary alcohol gives

A. a ketone B. an aldehyde C. an ester D. an alkane E. an ether

212. Phenol is more acidic than ethanol because

A. it has a higher molar mass B. the phenoxide ion is stabilized by resonance C. it contains a benzene ring that repels electrons D. it is a stronger nucleophile E. it is insoluble in water

213. 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

214. 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

215. 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

216. 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

217. 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

218. 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

219. Which of the following is a reducing sugar?

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

220. The percentage of nitrogen in urea is about

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

221. Depletion of stratospheric ozone is mainly caused by

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

222. 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

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

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

224. 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

225. The molar mass of carbon dioxide is

A. 28 g mol-1 B. 32 g mol-1 C. 44 g mol-1 D. 48 g mol-1 E. 12 g mol-1

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