multiple choice correct answers

Question 1

Which alternative is an example of a closed dynamic equilibrium?
(A) Two groups of students lining up opposite each other across a basketball court swapping sides one at a time.
(B) Water evaporating from a tree being replaced by water from the ground through the tree’s roots.
(C) Marbles rolling down a slope into a bucket.
(D) Water evaporating from a swimming pool being replaced with water from a hose.

Answer 1

A - Example models the idea that the rate of

reaction is equal in the forward and reverse

Question 2

How many isomers exist for C5H12?
(A) 1
(B) 2
(C) 3
(D) 4

Answer 2

C

Question 3

The conjugate acid of dihydrogen phosphate (H2PO4-) is:
(A) PO43-
(B) HPO42-
(C) H3PO4
(D) H3O+

Answer 3

B -The conjugate acid means is must have an extra
hydrogen and reduce the negative charge by
one.

Question 4

During dynamic equilibrium:

a) The forward reaction is greater than the reverse reaction
b) The reaction is incomplete, and all products are present in the equilibrium mixture
c) The reaction is static and not changing
d) At the molecular level, the bonds being broken and new bonds are being formed; reactants and products continue to be converted from one to the other.

Answer 4

D - At the molecular level, the bonds being
broken and new bonds are being formed;
reactants and products continue to be
converted from one to the other.

Question 5

Name the compound in the figure below:

Cl – CH2 – CH2 - Br

a) 1-chloro-2-bromoethane
b) 1-bromo-2-chloroethane
c) 1,2-chlorobromoethane
d) 1,2-bromochloroethane

Answer 5

B - Can’t distinguish between the two halogens by
point of difference (numbering) so have to
use alphabet.

Question 6

How many position isomers are possible for the following compound?

CH3 – CHBr – CH2 – CH3

a) 1
b) 2
c) 3
d) 4

Answer 6

B - Can exits on any of the four carbos but
Carbon 1 is the same as carbon 4 and carbon 2
= carbon 3

Question 7

Combustion reactions are irreversible exothermic reactions, such as the combustion of octane:

C8H18(g)+ O2(g) → 8CO2(g) + 9H2O(g)

Entropy tends to increase because:

a) The number of particles increases
b) The number of particles decreases
c) Combustion reactions are equilibrium reactions
d) Combustion reactions do not go to completion.

Answer 7

A - Entropy is level of disorder – more “things”
means a greater number of energy arrangements
= greater entropy

Question 8

At equilibrium, the value of the reaction quotient is equal to the equilibrium constant, Keq.
Generally, at equilibrium for chemical reactions:
a) The size of Keq does not demonstrate the relative amounts of reactants to products in the equilibrium mixture.
b) The same chemical reactions have different values of Keq
c) Different chemical reactions have different values of Keq
d) Keq is constant at any temperature for all reactions and for all equilibrium mixtures

Answer 8

C - Different chemical reactions have different

values of Keq

Question 9

A solution of HCl has a concentration of 0.002 molL-1 at 25°C. What is the pOH of the solution?
A. 11.0
B. 11.3
C. 2.7
D. 2.5

Answer 9

B - pH = -log [H+]
pH = -log [0.002M] as HCl is a strong acid
pH = 2.7
pH + pOH = 14 
pOH = 14 - pH
pOH = 14 - 2.7 =11.3

Question 10

Which anion will produce a precipitate when added to a barium nitrate solution?
A) Cl-
B) Ag+
C) Cu2+
D) SO42-

Answer 10

D - Use the data sheet – only one there is barium

sulfate