Suppose Earth's atmosphere had no greenhouse gases. Then Earth's ...

[savannahhooper]

Suppose Earth's atmosphere had no greenhouse gases. Then Earth's average surface temperature would be
 
  A) 250 K, which is well below freezing.
  B) 273 K, or about the freezing point for water.
  C) 283 K, or about 5 K cooler than it is now.
  D) 288 K, or about the same as it is now.
  E) 293 K, or about 5 K warmer than it is now.

Question 2

Mars' magnetic field is so weak because
 
  A) it spins much slower than Earth does.
  B) it core may no longer be molten.
  C) its core contains less iron than our own.
  D) Both B and C are probable.
  E) All of the above are correct.

[abro1885]

Answer to Question 1

A

Answer to Question 2

D