The Life Cycle Of A Star Reading Answers

Dec 13, 2022

The Life Cycle Of A Star Reading Answers contains paragaphs and 13 different types of questions. Candidates will be shown various question types with clear instructions in this IELTS Section. The Life Cycle Of A Star Reading Answers comprises of three types of questions: Matching heading, sentence completion, and Choose the correct option. For the Matching heading, candidates need to thoroughly go through each passage. For sentence completion, candidates need to skim the passage for keywords and understand the concept. To choose the correct option, candidates must read the IELTS Reading passage and understand the statement provided.

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Section 1

Read the Passage to Answer the Following Questions

The Life Cycle Of A Star Reading Answers

It has been conservatively estimated that there are some 10,000 billion stars in the universe. It is difficult to know the exact age of a star (astronomers have identified stars as young as 25,000 years old and others are thought to be over 10 billion years old), but what astronomers do know is that there are many different kinds.

How each star is formed, and its mass, influences its type and longevity. A star is born in a nebula, which is a giant cloud of gas and dust. The larger the amount of matter that is into the nebula, the greater the mass of the star that is created. Inside these nebulae are dense areas of gas, which, due to their density, have a stronger gravitational pull than the rest of the nebula. Gradually, gravity drags the gas in the nebula together and it begins to spin and become increasingly hotter.

Once the temperature reaches 15,000,000°C, nuclear fusion occurs in the center of the cloud and it begins to glow brightly. It stabilizes at this temperature, contracts slightly, and becomes what is known as a main-sequence star (an example of this is our own Sun). It can remain in this stage for millions or billions of years.

As it glows, hydrogen in the center (through nuclear fusion) becomes helium. Eventually, the hydrogen supply in the core diminishes and the core of the star becomes unstable, contracting more. However, the outer parts of the star (which are still mainly hydrogen) expand and cool, and in doing so, the star starts to glow red.

It is at this stage that the star becomes a red giant. It is anticipated that it will take the Sun another 5 billion years to reach this stage. By then it will have grown large enough to engulf the three closest planets (Mercury, Venus, and Earth) and glow 2,000 times brighter than it currently does.

Exactly how a star will react in the red giant phase depends on its mass. Throughout the red giant phase, the hydrogen in the outer parts carries on burning, and the center gets hotter and hotter. On reaching 200,000,000°C, the helium atoms fuse forming carbon atoms. The remainder of the hydrogen explodes and forms a ring around the core called a planetary nebula.

With medium-sized stars, once the final helium atoms have fused into carbon atoms, the star starts to die. The gravitational pull leads to the last of the star's matter collapsing inwards and compacting to become extremely dense. A star like this is called a white dwarf. It will shine white- hot until the remaining energy (thermal energy trapped in its interior) has been exhausted after which it will no longer emit light. This can take in excess of several billion years. It is then termed a black dwarf (a cold, dark star, perhaps replete with diamonds) and remains in that stage forever.

When the larger red giants (massive stars) collapse, which happens in an instant, so much planetary nebula is created that this gas and dust can be used as a building material for planets in developing solar systems. In addition, with massive stars, as the temperature increases, the Carbon atoms get pulled together to form increasingly heavier elements like oxygen, nitrogen, and finally iron. Once this happens, fusion ceases and the iron atoms begin absorbing energy. At some point in the future, this energy is released in a huge explosion called a supernova. A supernova can have a core temperature of up to 1,000,000,000°C and the explosion can light up the sky for weeks, outshining an entire galaxy. Astronomers believe that Earth is made up of elements formed from the inside of stars, in particular, red giants that explode as supernovas. These massive stars have an average lifespan of one million years.

After becoming a supernova, the remaining core of a massive star that is 1.5 to 4 times as massive as the Sun becomes a neutron star. It starts to spin and often emits radio waves. If these waves occur in pulses, the neutron star is referred to as a pulsar. When a massive star has eight or more times the mass of the Sun, it will remain massive after the supernova. It has no nuclear fusion at the core and becomes engulfed by its own gravity. This results in a black hole, which sucks in any matter or energy that passes close to it. The gravitational field of a black hole is powerful enough to prevent the escape of light and is so dense that it cannot be measured. The phrase ‘black hole’ originated from the physicist John Archibald Wheeler; before this, black holes were known as ‘frozen stars.’ Wheeler came up with this name two years before the proof of the existence of the first black hole, X-ray binary star Cygnus X-1, in 1971. Astronomers think that there may be a black hole at the center of each galaxy.

The life cycle of a star is really that — the materials from an exploded star mix with the hydrogen of the universe. This mixture, in turn, will be the starting point of the next star. The Sun is a case in point, containing the debris from numerous other stars that exploded long before the Sun was born.

Section 2

Solution with Explanation
Questions 1 – 6:

Different stages and types of stars are mentioned in Reading Passage 1. Choose ONE of the types or stages (A–H) from the box below that best matches the descriptions. NOTE: you may use any answer more than once.

nebula
main-sequence star
red giant
white dwarf
black dwarf
supernova
neutron star
black hole

Example: hottest, brightest point of a star Answer: F

the Sun _________

Answer: B
Supporting Statement: when the temperature reaches 15,000,000°C, nuclear fusion occurs in the center of the cloud and it begins to glow brightly. It stabilizes at this temperature, contracts slightly, and becomes what is known as a main-sequence star (an example of this is our own Sun).
Keywords: nuclear fusion, stabilize, main-sequence star.
Keyword location: Paragraph 3, line 3
Explanation: These lines imply that nuclear fusion takes place at the cloud's center when it starts to light brilliantly and that as the cloud stabilizes and contracts, it turns into a main-sequence star. The main-sequence star is the sun as a result. The solution is B, thus.

birthplace of a star _________

Answer: A
Supporting Statement: a star is born in a nebula, which is a giant cloud of gas and dust.
Keywords: star, Nebula, giant cloud of gas.
Keyword location: Paragraph 2, line 2
Explanation: We know that a nebula, that is a huge cloud of gas and dust, is where a star is born. So, the response is A.

a dying star _________

Answer: D
Supporting Statement: with medium-sized stars, once the final helium atoms have fused into carbon atoms, the star starts to die. The gravitational pull leads to the last of the star’s matter collapsing inwards and compacting to become extremely dense. A star like this is called a white dwarf.
Keywords: medium-sized stars, helium atoms, gravitational pull, white dwarf.
Keyword location: Paragraph 7
Explanation: According to these lines, the medium-sized stars begin to die when helium atoms combine with carbon atoms. A star like this is hence referred to as a white dwarf. The solution is D, thus.

sometimes has pulsating waves _________

Answer: G
Supporting Statement: after becoming a supernova, the remaining core of a massive star that is 1.5 to 4 times as massive as the Sun becomes a neutron star. It starts to spin and often emits radio waves.
Keywords: supernova, massive star, neutron star.
Keyword location: Paragraph 9
Explanation: These lines imply that when a star explodes as a supernova, its core grows to the size of the Sun, transforming it into a neutron star that spins and emits radio waves. Thus, neutron stars occasionally produce pulsating waves. Therefore, G is the correct response.

its size is immeasurable _________

Answer: H
Supporting Statement: the gravitational field of a black hole is powerful enough to prevent the escape of light and is so dense that it cannot be measured.
Keywords: gravitational field, black hole, escape of light
Keyword location: Paragraph 9, line 8
Explanation: These lines imply that a black hole's gravitational field is highly potent, preventing light from escaping, and extremely dense, making it impossible to measure. The black hole's size is therefore unknowable. The solution is H, thus.

its supply of energy has run out _________

Answer: E
Supporting Statement: the white star will shine white-hot until the remaining energy (thermal energy trapped in its interior) has been exhausted after which it will no longer emit light. This can take in excess of several billion years. It is then termed a black dwarf (a cold, dark star, perhaps replete with diamonds) and remains in that stage forever.
Keywords: white star, black dwarf, several billion years.
Keyword location: Paragraph 7, line 4
Explanation: These lines suggest that the white star will shine brightly up until the point at which the energy becomes trapped, at which point it stops emitting light. This process, known as a black dwarf, lasts a billion years and never changes stages. So, the response is E.

Questions 7 – 13:
Complete the sentences using NO MORE THAN THREE WORDS for each answer. Write your boxes 7 – 13 on your Answer Sheet.

Hydrogen will turn into helium after _____ occurs.

Answer: nuclear fusion
Supporting Statement: as it glows, hydrogen in the center (through nuclear fusion) becomes helium.
Keywords: hydrogen, helium.
Keyword location: Paragraph 4
Explanation: These lines show that nuclear fusion will result in the transformation of hydrogen into helium. Therefore, nuclear fusion is the solution.

The color of the red giant is formed as the ___ becomes smaller and the outer areas cool.

Answer: core
Supporting Statement: throughout the red giant phase, the hydrogen in the outer parts carries on burning, and the center gets hotter and hotter. On reaching 200,000,000°C, the helium atoms fuse forming carbon atoms. The remainder of the hydrogen explodes and forms a ring around the core called a planetary nebula.
Keywords: hydrogen, helium atoms, carbon atoms, planetary nebulae.
Keyword location: Paragraph 6
Explanation: From these lines, we can infer that during the red giant phase, the hydrogen in the outer regions continues to burn, making the center hot. When the center reaches a higher temperature, the helium atoms fuse to form carbon atoms, and the remaining hydrogen explodes to form a ring around the core known as a planetary nebula. As a result, the red giant's color develops as its outer regions cool and its core shrinks. So the core of the response.

At 200,000,000°C the star’s helium atoms fuse into carbon atoms, and then the star____.

Answer: starts to die
Supporting Statement: the helium atoms fuse forming carbon atoms when it reaches 200,000,000°C and the remainder of the hydrogen explodes and forms a ring around the core called a planetary nebula. When the final helium atoms have fused into carbon atoms with medium-sized stars, the star starts to die.
Keywords: helium atoms, carbon atoms, hydrogen explodes, planetary nebula.
Keyword location: Paragraph 6 – 7
Explanation: These lines show that the star begins to die when the temperature exceeds 200,000,000 C, when the helium atoms fuse into carbon atoms. The response therefore, starts to die.

Unlike small and medium-sized stars, large stars ______quickly.

Answer: collapse
Supporting Statement: when the larger red giants (massive stars) collapse, which happens in an instant, so much planetary nebula is created that this gas and dust can be used as a building material for planets in developing solar systems.
Keywords: red giants, planetary nebula, solar systems.
Keyword location: Paragraph 8
Explanation: These lines imply that, in contrast to small and medium-sized stars, massive stars rapidly collapse and numerous planetary nebulae are produced. So, collapse is the answer.

A black hole’s ________ stops light from being emitted.

Answer: the gravitational field
Supporting Statement: the gravitational field of a black hole is powerful enough to prevent the escape of light and is so dense that it cannot be measured.
Keywords: gravitational field, black hole, escape of light.
Keyword location: Paragraph 7, line 8
Explanation: These lines tell us that the gravitational field of a black hole is so strong that light cannot escape and is so dense that it is unmeasurable. The gravitational field is the solution as a result.

Astronomers knew about _______ before they were able to confirm their existence.

Answer: black holes
Supporting Statement: Wheeler came up with this name two years before the proof of the existence of the first black hole, X-ray binary star Cygnus X-1, in 1971. Astronomers think that there may be a black hole at the center of each galaxy.
Keywords: wheeler, first black hole, cygnus
Keyword location: Paragraph 7,last line
Explanation: These words imply that Wheeler showed up with the moniker before the first black hole's existence was established. As a result, astronomers think that each galaxy may contain a black hole at its core. As a result, astronomers were aware of the black hole before they were able to verify it. A black hole is the solution as a result.

Planets and stars are likely to consist of _______ from exploded celestial bodies.

Answer: debris/ materials
Supporting Statement: the fact that the life cycle of a star is really that — the materials from an exploded star mix with the hydrogen of the universe. This mixture, in turn, will be the starting point of the next star. The Sun is a case in point, containing the debris from numerous other stars that exploded long before the Sun was born.
Keywords: hydrogen, sun, exploded.
Keyword location: Paragraph 10
Explanation: From these lines, we can infer that the components of an exploding star are combined with the universe's hydrogen, which will serve as the nucleus of the following star. In this instance, the Sun is home to pieces of multiple other stars that burst before the Sun even existed. Therefore, it is likely that the planets and stars are made of leftover pieces and components from exploding celestial entities. So the answer is materials or debris.

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