WAEC Chemistry Past Questions & Answers - Page 154

766.

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.

767.

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 .

768.

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.

769.

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.

770.

In a fixed volume of a gas, an increase in temperature results in an increase in pressure due to an increase in the

A.

number of the collisions between the gas molecules and the walls of the container

B.

kinetic energy of the gas

C.

number of collisions between the gas molecules

D.

number of repulsion between the gas molecules

Correct answer is A

No explanation has been provided for this answer.