Question

balloons powered by science
up, up, and away! hot - air balloons fascinate, amaze, and delight people of all ages. these colorful creations seem to float effortlessly across a clear blue sky. yet they are strong enough to support multiple passengers and equipment. how is that possible? it all comes down to one thing - science.
hot - air balloons are based on a single concept: warm air rises and cool air falls. this is because cold air is denser than warm air. density is defined as the ratio of mass to volume; it tells us how many molecules occupy a space at one time. the more molecules there are in a given volume, the denser the substance. the fewer molecules there are, the less dense the substance is. warm air, in which the molecules are farther apart, is less dense than cold air. for liquids and gases, a substance that has greater density sinks to the bottom.
hot - air balloons carry passengers high above the ground.
question #17
which detail from the passage best reveals the authors opinion about hot - air balloons?
1.
evertheless, humans have found many uses for balloons since the first piloted one took flight in 1783.\ (paragraph 4)

1. \many agencies now use hydrogen - or helium - filled balloons to conduct research in this manner.\ (paragraph 5)
2. \these helium - filled, super - pressure balloons circle the continent of antarctica up to three times before returning to earth.\ (paragraph 6)
3. \for passengers, a hot - air - balloon ride offers an amazing view of the world and a memorable lesson in science.\ (paragraph 7)

Explanation:

The passage expresses wonder and fascination with hot - air balloons, such as their ability to carry passengers and their long - standing appeal. The statement "For passengers, a hot - air - balloon ride offers an amazing view of the world and a memorable lesson in science." shows the author's positive opinion.

Answer:

1. "For passengers, a hot - air - balloon ride offers an amazing view of the world and a memorable lesson in science." (Paragraph 7)