Just t$'o months after lhe flisht otApollo /r, the/lpollo /1 asn'onauts made their hisloric
landing on the surlace ofthe Moon. Thi! monentous trip lor humanitv a]so provided scienlisls with
an abundance of material for study; toom rock and soil sanples brousht back fiom the Moon,
:r scientists have been able to determine much about the composilion of the MooD as well as 1() draw
. inierences about the development ol lbe Moon fion its composition
The Moon soii that came back on APllo L/ contains snall bits ofrock and glass which were
probably ground hom larger rocks $'hen neteors impacted with the surlace ol the Moon The bits of
glass arc spherical in shape and constilute approxinalely halfofthe Moon soil. Scieniists iound no
lrace o{animal or plant life in this soil
In addition to the Moon soil, astronauls gathered two basic lypes olrocks from the suriace of
the Moon: basall and breccia. Basalt is a cooled and hadened volcanic lava common lo the Earlh.
Since basalt is iormed under ext.emely high lemperatures, the presence ofthis lvpe ofrock is an
indicalion lhat the temperallrre ol thc Moon was once ertremelY hot Breccia the other kind oirock
broughl back by the aslronauts, was tormed durins ihe impact of fallins objecrs on the surface of the
i Moon. This second lype olrock consisls of small pieccs of rock compressed tosether bv lhe torce of
impact. Gases such as hJdroeen and helirm were found in some olthe rocks and scicnlists believe
that these gases uere canied lcl the Moon by the solar wind, lhe streams of gases thal are constantlv
emitted bv the Sun-
20. The paragraph preceding the passage mosl
likely discusses
(A) astronaull'-ainine
(B) the inceplion cltheApo o sPace
program
(C) a differenr space rip
(D) prcvious Moon landinss
2 l Wha! is the subject ol this passasc?
(A) The Apolo astronauts
(B) Soil on the Moon
(c) Whar the Moon is made ol
(D) Basalt and breccia
22. An "abundance" in line 3 is
(A) a disoderly pile
(B) a uealthy bunch
(C) an insisnificanl Proportiotl
(D) a larse amount
23. According 1o the passage, what does Moon
soil consist oi?
(A) Hydro-qen and helium
(B) Larye chunks olvolcanic lala
(C) Tiny pieces of slones and slass
(D) Slreams ofeases