346 ❯ STEP 5. Build Your Test-Taking Confidence- The analysis of a sample contaminated with
NaHCO 3 gave slightly different results. How
does the volume of acid necessary to reach G
from 0 compare to the volume of acid necessary
to get from G to H for the second sample?
(A) It takes more to get from G to H.
(B) It takes more to reach point G.
(C) They are the same.
(D) It is impossible to determine. - How could a student determine if there was a
strong acid or a strong base contaminant in the
original sample?
(A) The presence of an acid contaminant would
require less acid to reach H from G than to
reach G from 0.
(B) The presence of a base contaminant would
require less acid to reach G from 0 than to
reach F from G.
(C) The presence of a base contaminant would
require more acid to reach G from 0 than
to reach F from G.
(D) It is impossible to determine. - In addition to water, what are the predominant
species in solution at F?
(A) Na 2 CO 3 and HCl
(B) Na+, Cl-, and H 2 CO 3
(C) HCO 3 - and H+
(D) Na+, Cl-, H+, and CO 32 - - At what point on the graph for the titration of
pure sodium carbonate is the pH = pKa2 for car-
bonic acid?
(A) At point G
(B) Halfway between the start and point G
(C) At point H
(D) Halfway between points G and H - Three steel containers hold gas samples. The
containers are all the same size and at the same
temperature. One container has 4.0 g of helium,
another has 28.0 g of nitrogen, and the third has
44.0 g of carbon dioxide. Pick the FALSE state-
ment from the following list:
(A) The densities increase in the order helium <
nitrogen < carbon dioxide.
(B) The number of molecules in all the contain-
ers is the same.
(C) The pressure in all three containers is the same.
(D) The average speed of all the molecules is the
same.
21. When potassium perchlorate, KClO 4 , dissolves
in water, the temperature of the resultant solu-
tion is lower than the initial temperature of the
components. Which of the following conclusions
may be related to this?
(A) This is a spontaneous process because it is
exothermic.
(B) This is a spontaneous process because of an
entropy increase.
(C) This is a spontaneous process because of an
entropy decrease.
(D) This is a spontaneous process because it is
exothermic.
22. The graph shows the variation of boiling point
with Group number for the hydrogen compounds
of the four lightest members of Group 15 on the
periodic table (NH 3 , PH 3 , AsH 3 and SbH 3 ).
–100–90–80–70–60–50–40–30–20–100
Group 15What is the reason that the lightest member of
Group 15 does not follow the trend of the other
members, which show that the boiling point
decreases with decreasing atomic mass of the
Group 15 element?
(A) Ionic bonds
(B) Hybrid orbitals
(C) Resonance structures
(D) Hydrogen bondingGO ON TO THE NEXT PAGE21-Moore_PE02_p341-370.indd 346 31/05/18 1:54 pm