Which of the following substances is a mixture?

A. Sulphur powder

B. Bronze

C. Distilled water

D. Ethanol

A balanced chemical equation obeys the law of?

A. conservation of mass

B. difinite proportions

C. multiple proportions

D. conservation of energy

How many moles of oxygen molecules would be produced from the decomposition of 2.50 moles of potassium trioxochlorate (V)?

A. 2.50

B. 3.50

C. 3.75

D. 7.50

For iodine crystals to sublime on heating, the molecules must acquire energy that is?

A. less than the forces odf attraction in the solid

B. equal to the forces of attraction in th solid

C. necessary to melt the solid

D. greater than the forces of attraction in both the solid and the liquid phases

An element, E, has the electronic configuration 1s²2s²2p⁶3s²p³. The reaction of E with a halogen X can give?

A. EX₃ and EX₅

B. EX₃ only

C. EX₅ only

D. EX₂ and EX₃

Two atoms represented as U and U are?

A. isomers

B. allotropes

C. isotopes

D. anomers

As the difference in electronegativity between bonded atoms increases, polarity of the bond?

A. decreases

B. increases

C. remains unchanged

D. reduces to zero

Which group of elements forms hydrides that are pyramidal in structure?

A. III

B. IV

C. V

D. VI

Water has a rather high boiling point despite its low molecular mass because of the presence of?

A. hydrogen bonding

B. covalent bonding

C. ionic bonding

D. metallic bonding

Argon is used in gas-filled electric lamp because it helps to?

A. prevent the reduction of the lamp fillaments

B. prevent oxidation of the lamp fillaments

C. make the lamp fillament glow brightly

D. keep the atmosphere in the lamp inert