WAEC Chemistry Past Questions & Answers - Page 162

806.

The colour of phenolphthalein indicator in dilute HNO is

A.

colourless

B.

orange

C.

pink

D.

purple

Correct answer is A

No explanation has been provided for this answer.

807.

Which of the following set of equations could be used to represent the standard enthalpy of formation of glucose?

A.

6C (s) + 6H 2(g) + 3O2(g) → C 6H12O6(s)

B.

6CO2(g) + 6H2O (l) → C6H12O6(s) + 6O 2(g)

C.

6C(g) + 6H 2(g) + 3O2(g) → C6H12O 6(s)

D.

6C(g) + 6H 2(g) + 3O2(g) → C 6H 12O 6(aq)

Correct answer is B

No explanation has been provided for this answer.

808.

Diamond does not conduct electricity because it?

A.

has no free valence electrons

B.

is a giant molecule

C.

contains no bonded electrons

D.

is a solid at room temperature

Correct answer is A

It does not conduct electricity. Every atom in a diamond is bonded to its neighbours by four strong covalent bonds, leaving no free electrons and no ions .

809.

The collision theory proposes that

A.

reactants collide more frequently to bring about reduction in the reaction rate

B.

all collisions of reactants are effective

C.

reactants must collide with a certain minimum amount of energy to from products

D.

the fewer the collisions the faster the reaction rate

Correct answer is C

No explanation has been provided for this answer.

810.

When concentrated H2
SO 4 is added to NaCI (s), the gas evolved

A.

bleaches damp blue litmus paper

B.

forms a white preciptate with AgNO3(aq)

C.

forms a white precipitate with BaCI2(aq)

D.

turns moist red litmus paper blue

Correct answer is A

No explanation has been provided for this answer.