Passage
4
1.
(C)
The
phrase "this element" refers to the parent element,
"uranium," mentioned in the previous sentence.
2.
(A)
A
liquid or gas "seeps" or "leaks" through holes or cracks.
3.
(A)
According
to paragraph 2, the health problems are caused by radon after it decays into its
radioactive particles. If it has not had time to decay, radon is harmless.
4.
(A)
When
a substance "disintegrates" or "breaks down," it changes
from one state into its simpler component parts.
5.
(C)
According
to the passage, heavy metals such as polonium, lead, and bismuth, which are
products of the decay process of radon, are what cause health problems.
6.
(A) "Unlike
the radon... " - The radon progeny are the products that gather together as
the radon disperses.
7.
(B)
According
to paragraph 3, products of decay, especially alpha particles, are dangerous
because they accumulate into concentrations instead of dispersing throughout the
body. In these concentrations, they "cannot penetrate living tissue"
and damage nearby cells.
8.
(B)
Radon
is described as a decay product of uranium and, therefore, is a uranium
daughter.
9.
(B)
It
can be understood that radon is detectable because buildings are tested for the
amount of radon that has accumulated.
10.
(C)
According
to paragraph 6, a reduction of radon can be achieved by using concrete sealing
and active ventilation systems.
11.
(A)
A
"prudent" or "sensible" action is one which is wise under
the circumstances.
12.
The
3RD
square.
The phrase "But this research" refers back to the research on radon
accumulation and cancer rates, and would follow the sentence mentioning this.
13.
(B)(D)(F)
b
"Concentrations...
" - After radon enters a building, its decay products form particles that
can be breathed into the lungs.
d
"The
by-product... " - The alpha particles, in particular, accumulate in the
lung tissue and damage cells.
f
"Preventative
measures... " - It is possible to reduce radon exposure, but some of the
gas stays in the atmosphere.