Passage Reading and English Comprehension

About twice every century, one of the massive stars in our galaxy blows itself apart in a supernova explosion that sends massive quantities of radiation and matter into space and generates shock waves that sweep through the arms of the galaxy. The shock waves heat the interstellar gas, evaporate small clouds, and compress larger ones to the point at which they collapse under their own gravity to form new stars. The general picture that has been developed for the supernova explosion and its aftermath goes something like this.

Throughout its evolution, a star is much like a leaky balloon. It keeps its equilibrium figure through a balance of internal pressure against the tendency to collapse under its own weight. The pressure is generated by nuclear reactions in the core of the star which must continually supply energy to balance the energy that leaks out in the form of radiation. Eventually the nuclear fuel is exhausted, and the pressure drops in the core. With nothing to hold it up, the matter in the center of the star collapses inward, creating higher and higher densities and temperatures, until the nuclei and electrons are fused into a super-dense lump of matter known as a neutron star.

As the overlying layers rain down on the surface of the neutron star, the temperature rises, until with a blinding flash of radiation, the collapse is reversed. A thermonuclear shock wave runs through the now expanding stellar envelope, fusing lighter elements into heavier ones and producing a brilliant visual outburst that can be as intense as the light of 10 billion suns. The shell of matter thrown off by the explosion plows through the surrounding gas, producing an expanding bubble of hot gas, with gas temperatures in the millions of degrees. This gas will emit most of its energy at X-ray wavelengths, so it is not surprising that X-ray observatories have provided some of the most useful insights into the nature of the supernova phenomenon. More than twenty supernova remnants have now been detected in X-ray studies.

Recent discoveries of meteorites with anomalous concentrations of certain isotopes indicate that a supernova might have precipitated the birth of our solar system more than four and a half billion years ago. Although the cloud that collapsed to form the Sun and the planets was composed primarily of hydrogen and helium, it also contained carbon, nitrogen, and oxygen, elements essential for life as we know it.

Elements heavier than helium are manufactured deep in the interior of stars and would, for the most part, remain there if it were not for the cataclysmic supernova explosions that blow giant stars apart. Additionally, supernovas produce clouds of high-energy particles called cosmic rays. These high-energy particles continually bombard the Earth and are responsible for many of the genetic mutations that are the driving force of the evolution of species.

1157. Which of the following titles best describes the content of the passage?

	(a) The Origins and Effects of Supernovas
	(b) The Life and Death of Stars
	(c) The Origins and Evolution of Life on Earth
	(d) The Aftermath of a Supernova

1158. According to the passage, we can expect a supernova to occur in our galaxy

	(a) about twice each year
	(b) hundreds of times each century
	(c) about once every fifty years
	(d) about once every other century

1159. According to the passage all of the following are true of supernovas EXCEPT that they

	(a) are extremely bright
	(b) are an explosion of some sort
	(c) emit large quantities of X-rays
	(d) are caused by the collision of large galaxies

1160. The author employs which of the following to develop the first paragraph?

	(a) Analogy
	(b) Deduction
	(c) Generalization
	(d) Example

1161. It can be inferred from the passage that the meteorites

	(a) contain dangerous concentrations of radioactive materials
	(b) give off large quantities of X-rays
	(c) include material not created in the normal development of our solar system
	(d) contain pieces of a supernova that occurred several billion years ago

1162. The author implies that

	(a) it is sometimes easier to detect supernovas by observation of the X-ray spectrum than by observation of visible wavelengths of light
	(b) life on Earth is endangered by its constant exposure to radiation forces that are released by a supernova
	(c) recently discovered meteorites indicate that the Earth and other planets of our solar system survived the explosion of a supernova several billion years ago
	(d) lighter elements are formed from heavier elements during a supernova as the heavier elements are torn apart

1163. According to the passage what is the first event in the sequence that leads to the occurrence of a supernova?

	(a) An ordinary star begins to emit tremendous quantities of X-rays
	(b) A neutron star is enveloped by a superheated cloud of gas
	(c) An imbalance between light and heavy elements causes an ordinary star to collapse
	(d) A cloud of interstellar gas rich in carbon, nitrogen, and oxygen, collapses to form a neutron star

1164. According to the passage a neutron star is

	(a) a gaseous cloud containing heavy elements
	(b) an intermediate stage between an ordinary star and a supernova
	(c) the residue that is left by a supernova
	(d) the core of an ordinary star that houses the thermonuclear reactions

1165. The author is primarily concerned with

	(a) speculating about the origins of our solar system
	(b) presenting evidence proving the existence of supernovas
	(c) discussing the nuclear reaction that occurs in the core of a star
	(d) describing the sequence of scientific events

TOTAL

Detailed Solution

1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20
21	22	23	24	25	26	27	28	29	30	31	32	33	34	35	36	37	38	39	40
41	42	43	44	45	46	47	48	49	50	51	52	53	54	55	56	57	58	59	60
61	62	63	64	65	66	67	68	69	70	71	72	73	74	75	76	77	78	79	80
81	82	83	84	85	86	87	88	89	90	91	92	93	94	95	96	97	98	99	100
101	102	103	104	105	106	107	108	109	110	111	112	113	114	115	116	117	118	119	120
121	122	123	124	125	126	127	128	129	130	131	132	133	134	135	136	137	138	139	140
141	142	143	144	145	146	147	148	149	150	151	152	153	154	155	156	157	158	159	160
161	162	163	164	165	166	167	168	169	170	171	172	173	174	175	176	177	178	179	180
181	182	183	184	185	186	187	188	189	190	191	192	193	194	195	196	197	198	199	200
201	202	203	204	205	206	207	208	209	210	211	212	213	214	215	216	217	218	219	220
221	222	223	224	225	226	227	228	229	230	231	232	233	234	235	236	237	238	239	240
241	242	243	244	245	246	247	248	249	250	251	252	253	254	255	256	257	258	259	260
261	262	263	264	265	266	267	268	269	270	271	272	273	274	275	276	277	278	279	280
281	282	283	284	285	286	287	288	289	290	291	292	293	294	295	296	297	298	299	300
301	302	303	304	305	306	307	308	309	310	311	312	313	314	315	316	317	318	319	320
321	322	323	324	325	326	327	328	329	330	331	332	333	334	335	336	337	338	339	340
341	342	343	344	345	346	347	348	349	350	351	352	353	354	355	356	357	358	359	360
361	362	363	364	365	366	367	368	369	370	371	372	373	374	375	376	377	378	379	380
381	382	383	384	385	386	387	388	389	390	391	392	393	394	395	396	397	398	399	400
401	402	403	404	405	406	407	408	409	410	411	412	413	414	415	416	417	418	419	420
421	422	423	424	425	426	427	428	429	430	431	432	433	434	435	436	437	438	439	440
441	442	443	444	445	446	447	448	449	450	451	452	453	454	455	456	457	458	459	460
461	462	463	464	465	466	467	468	469	470	471	472	473	474	475	476	477	478	479	480
481	482	483	484	485	486	487	488	489	490	491	492	433	494	495	496	497	498	499	500

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