Cover of the textbook Performer B2 - Student's Book

The key answer of exercise 1

The key to exercise solutions in chapter 7 - Listening for the textbook Performer B2 - Student's Book with authors Marina Spiazzi, Marina Tavella, Margaret Layton from Zanichelli

Question

Discuss in pairs. Decide whether these scientific facts are true or not.

Answer

  1. True. Clouds consist of tiny water droplets or ice crystals suspended in the atmosphere, and their collective mass can be substantial, comparable to the weight of large aircraft.
  2. Likely true. Earth is teeming with microorganisms such as bacteria, fungi, and protists, many of which inhabit soil, making it plausible that there are more microorganisms in a teaspoon of earth than there are people on the planet.
  3. True. Research has shown that rats emit ultrasonic vocalizations resembling laughter when tickled, indicating positive social interaction analogous to human laughter.
  4. Controversial. While commonly believed, the Mpemba effect suggests that under certain conditions, hot water can freeze faster than cold water, though the circumstances are not fully understood.
  5. Likely true. Estimates suggest a vast number of stars in the Milky Way galaxy, likely outnumbering the estimated number of trees on Earth.