~
Passage I
2. The greatestelectronegativityin the tableis:
The tablebelow showsselectedelementsfrom the
periodic table, together with their atomic radii in
angstromunits (A) and their electronegativities(second
number):
F.
G.
H.
J.
fluorine (F).
chlorine(Cl).
rubidium (Rb).
hydrogen(H).
3. The bond length in the P-CI bond is
Be
B
0.90 A 0.80 A
1.57~
Mg
AI
1.30A t.25 A
, 1.31 . 1.61
Si
1.17A
1.90
~
N
0
F
0.70 A 0.66 A 0.64 A
3.04 i 3.44
3.98
P
S
1.IOA 1.04A
'9~ A.
2.19
2.58
3.16
Br
1.14A.
~I
I
1.33A
, 2.66 ,
When two atoms form a covalentbond, the
approximatebond length may be calculatedby adding
togetherthe two atomic radii.
The electronegativity has important chemical
significance. If two atoms form a bond, the difference
in the two electronegativitiesindicates the degreeto
which the bond is covalent (indicated by a small
difference)or ionic (indicatedby a largedifference).
According to the chart, as one moves down a
column in the table, which of the following
occur?
A. the radii decreaseand the
decrease
B. the radii increaseand the
increase
r~. the radii decreaseand the
increase
D. the radii increaseand the
decrease
A.
B.
C.
D.
0.11 angstroms,
0.97 angstroms.
2.09 angstroms.
5.35 angstroms.
4. The bond between which of the following is
likely to havethe mostcovalentcharacter?
F.
G.
H.
J.
Sodium(Na) andiodine(1)
Magnesium(Mg) andoxygen(0)
Sulphur(S) andoxygen(0)
Carbon(C) and nitrogen(N)
5. The table indicatesthat bonds of greatestionic
characteroccur:
A. betweenelementsby eachother in a row.
B. betweenelementsthat areneareachotherin a
column but far apartalong a row.
C. betweenelementsthat are far apart along a
column but close in a row.
D. betweenelementsfar apart along a column
andfar apartin a row.
electronegativities
electronegativities
electronegativities
electronegativities
6 The element cesium (Cs) lies directly below
rubidium (Rb) in the Periodic Table. The
electronegativitydifferencein CsF is likely to be:
F.
G.
H.
J.
lessthan 3.16.
equal to 3.16.
greaterthan 3.16.
Cannotbedetermined
GO ON TO THE NEXT PAGE
A-94 ACT PRACTICETEST II
Passage VII
9
The following are two theories regarding the
proportions of chemicals that will react to form
products.
Theory 1
Although a chemicalreactionis morethan simple
mixing, the two are similar in that any amounts of
reactantsmay be brought together to form chemical
products that contain the same elements as the
reactants.For example,in the reaction
An experimenterfinds that when 170g of AgNO3
is reactedwith 58.5 g of NaCI to form products,
none of the original reactants remain in
appreciableamounts. When the original amount
of AgNO3 is increasedto 175 g, then all of the
NaCI is used up, but 5 g of AgNO3 remains.
This result is:
A.
B.
C.
D.
consistentwith Theory 1.
consistentwith Theory 2.
consistentwith both Theory 1 andTheory2.
not consistentwith either theory.
hydrogen+ oxygen~ water
we may use 1 mole of hydrogenand 1 mole of oxygen,
or 2 to I, or 1 to 2, etc. The reactionwill adjust to the
proportionsgi Yen.
Theory 2
Only certain proportions of reactants will
combinechemically. For example,when hydrogenand
oxygenarereacted,the amountsthat will combine will
be exactly 2 g of hydrogenfor every 32 g of oxygen.
We can show, using molecular weights, that these
weights of reactants(which correspondto 2 moles of
hydrogenand 1 mole of oxygen), imply the following
reaction:"
2H2+ O2~ 2H2O
From this statement about the proportions of
hydrogensand oxygensthat react with eachother, we
can concludethat two hydrogenmoleculesmust react
with a single oxygen moleculeto form two molecules
of water.
7. Which
of the following is NOT prooictedby
Theory I?
A. 2 molesof zinc may reactcompletely with 2
molesof sulfur.
B. 2 molesof zinc may reactcompletely with 3
molesof sulfur.
C. 7 molesof zinc may reactcompletely with 4
molesof sulfur.
D. If 3 moles of zinc weremixed with 4 moles
of sulfur. 1 mole of sulfur would be left
unreactoo.
8 . According
to TheorybyI,the
how
many moles
of water
would be produced
reaction
of 2 moles
of
hydrogen and 1 mole of oxygen?
F. 1
G. 2
H. 4
Cannot be determined
10. Accordingto Theory 2, how might the remaining
5 g of AgNO3be usedup?
F.
G.
H.
J.
-
Add moreof the reactantNaCI.
Removesomeof the reactantNaCI.
Add evenmoreof the reactantAgNO3.
Thereis no mechanismfor using the 5g of
AgNO3.
An experimenter wishes to determine which
theory better fits her data for an experiment in
which iron (Fe) is chemically combined with
oxygen (0). She finds that 2 moles of Fe will
reactcompletely with 2 moles of 0; she also
finds that 2 moles of Fe will react completely
with 3 molesof O. At this point she is confident
that Theory I, which is in opposition to the idea
of "definite proportions,"is correct. What further
experimentmight she do to test the successof
Theory lover Theory2?
A.
B.
C.
D.
Add 1 mole of Fe to 1 mole of O.
Add 2 molesof Fe to 4 molesof o.
Add 3 molesof Fe to 4.5 molesof O.
Add 4 molesof Fe to 4 molesof O.
12. Accordingto Theory I, the productof the reaction
of hydrogenandoxygen:
F. is H2O
G. could be anything.
H. mustcontainhydrogenandoxygen, but lacks
a specificformula.
J. has a definite proportion of hydrogen to
oxygen.