Hi everyone, let’s try to answer this question. This is one of the hardest TOEFL reading questions as it requires you to synthesize information from various parts of the paragraph.
To solve a question, you should first read the question and understand what it is asking you to do. As it has "supports," you know that this is an inference question. It asks you to find a true statement related to the ability of planets to retain gases.
Now that we understand the question, let’s skim the passage paying attention to phrases relating to retain gases.
The first two sentences establish facts:
Jovian planets have thick atmospheres, and made of many different gases
Terrestrial planets have thin atmospheres. the passage doesn’t say what the atmosphere is made of.
Based on these two facts, we can guess that the rest of the paragraph should be about why this is the case, that is, the Jovian planets retain a lot of ases, and terrestrial planets have only a little bit of gases.
It says that “ A planet's ability to retain an atmosphere depends on its temperature and mass.”
Ability to retain gasses = Temperature + Mass
It introduces a terminology, Escape Velocity. Whenever you see any technical term, skip it as it will not be asked in the question. it is a filler. All you need to know is some fact that makes sense you you like this:
the escape velocity of Earth = 11 km
the escape velocity of the Jovian planets = 21 - 60 km
“Consequently” explains why Jovian planets have thick atmospheres.
“Also” introduces a different item, which is temperature. So we know that so far it was about how the mass of a planet affects the planet’s ability to retain gas. It says that Jovian planets are cold, so “even the lightest gases are unlikely to acquire the speed needed to escape.” What does this mean?
Pay attention here. Many TOEFL questions basically ask whether you understand the meaning of “even.” "Even" signals an unusual thing, a surprise. Like when Caesar said “Even you, Brutus?” It means Caesar did not expect that Brutus would betray him. Also, “Even Beyoncé was at the party” means I didn’t expect that Beyoncé would be there, but there she was! So, “even the lightest gases are unlikely to acquire the speed needed to escape” means that “if the lightest gases cannot escape, of course, heavy gases cannot escape either.” That is, from this, you need to be able to infer this:
Jovian planets are cold → retain lightest as well as heavy gases.
The paragraph then compares this fact with two other cases: with the Moon and with other terrestrial planets. The Moon is light and warm, so there are no gases. Terrestrial planets are larger than the Moon, so they can only retain heavy gases.
Moon → light and warm → no gases
Terrestrial planets = larger than Moon → only heavy gases
So these three are the things we know about the planet's ability to retain gaeses. Now, let’s consider the options.
More-massive planets are less able to retain gases than less-massive ones.
A is wrong. Heavier planets will retain more gases since the escape velocity is proportional to temperature and mass
All planets are more likely to retain heavy gases than light gases.
Jovian planets have heavy and light gases, and terrestrial planets have only heavy gases, so all planets must have heavy gases. So B is correct. Even though B uses the extreme word "all," this statement is not absolute because it is qualified by "likely." That is, this sentence does not make an absolute statement..
Jovian planets are unlikely to retain the lightest gases.
C is false. Jovian can retain even the lightest gases.
Only terrestrial planets have been able to retain carbon dioxide.
D is not true as it contradicts B.
If you are an astronomy or chemistry buff, you might be able to deduce B from reading just the first two sentences.
Jovian planets = thick atmosphere: made of many different types of gases (light and heavy)
Terrestrial = thin atmosphere: made of some heavy gases
If you are not a scene buff, and absolutely paralyzed by the technical term, escape velocity, and decide to choose one, use the following strategy to evaluate the options.
More-massive planets are less able to retain gases than less-massive ones.
A should not sound not right since the passage said that Jovian planets have thick atmospheres, which means that they retain a lot of gases. You know that Jovian planets are very big (massive) compared with the earth. So you know that massive planets are more likely, not less likely, to be apple to retain gases. So, you can eliminate A.
All planets are more likely to retain heavy gases than light gases.
You cannot know whether B is true since you are just guessing. But you cannot throw it away either since B is nicely qualified with “likely.”Thanks to “likely,” even if there are exceptions, the exceptions do not make the sentence fasle. (Remember how much Dr. Byrnes emphasize that you should pay attention to qualifiers for information, inference and summary questions)
Jovian planets are unlikely to retain the lightest gases.
C: is false since the first sentence states that they have hydrogen and if you learned chemistry in high school, you know that hydrogen is the lightest gas.
Only terrestrial planets have been able to retain carbon dioxide.
D is a trap. Pay attention to the absolute word "only." Without only, “terrestrial planets have been able to retain carbon dioxide” is true, as it is explicitly mentioned here. However, "only" implies that Jovian planets are unable to retain carbon dioxide, but we know this is false since gases of Jovian planets contain both heavy and light gases.
So the moral is that if an option repeats almost exactly the same thing mentioned in the passage, it is almost always a trap. Remember the saying "if something sounds too good, they usually are not true."