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Showing 1576 to 1600 of 3046 questions (page 64 of 122).

1576. Boron trifluoride acts as a Lewis acid because boron

A. has a lone pair B. is highly electronegative C. forms hydrogen bonds D. has an incomplete octet E. is a metal

1577. Aluminium oxide is described as amphoteric because it reacts with

A. bases only B. both acids and bases C. neither acids nor bases D. acids only E. water only

1578. The reluctance of the ns2 electrons to take part in bonding in heavier p-block elements is called

A. hyperconjugation B. the shielding effect C. the inert pair effect D. the lanthanide contraction E. the diagonal relationship

1579. The strongest oxidizing agent among the halogens is

A. astatine B. iodine C. chlorine D. bromine E. fluorine

1580. Bleaching powder is prepared by passing chlorine over

A. dry slaked lime B. quicklime C. calcium sulphate D. sodium hydroxide solution E. limestone

1581. Which oxide of nitrogen is known as laughing gas?

A. NO2 B. N2O C. N2O5 D. NO E. N2O3

1582. A transition element is one that has a partially filled

A. s subshell B. valence shell of eight electrons C. d subshell D. f subshell E. p subshell

1583. The colour of most transition metal ions in solution is due to

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

1584. In the complex ion hexaamminecobalt(III), the coordination number of cobalt is

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

1585. EDTA is an example of a

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

1586. Transition metals show variable oxidation states because

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

1587. The hybridization of each carbon atom in ethene is

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

1588. The halogenation of alkanes in sunlight proceeds by a

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

1589. According to Markownikoff's rule, addition of hydrogen bromide to propene gives mainly

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

1590. Benzene characteristically undergoes

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

1591. A primary alkyl halide reacting with a strong nucleophile typically follows

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

1592. A Grignard reagent has the general formula

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

1593. Controlled oxidation of a primary alcohol gives

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

1594. 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

1595. Tollen's reagent is used to distinguish

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

1596. Carboxylic acids are more acidic than alcohols because

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

1597. The reaction of a carboxylic acid with an alcohol in the presence of an acid catalyst is called

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

1598. At its isoelectric point, an amino acid exists mainly as

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

1599. The linkage joining amino acid residues in a protein is

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

1600. Nylon 6,6 is an example of

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

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