The mass number of an atom is determined by the weight of: a. ...

[HudsonKB16]

The mass number of an atom is determined by the weight of:
 
  a. neutrons and protons
  b. neutrons and electrons
  c. protons and electrons
  d. protons only
  e. neutrons only

Question 2

Why is carbon dioxide important in maintaining a greenhouse effect?
 
  What will be an ideal response?

[wtf444]

Answer to Question 1

a

Answer to Question 2

Earth's atmosphere is transparent to sunlight, and when the ground absorbs the sunlight, it grows warmer and radiates at infrared wavelengths. However, CO2 makes the atmosphere less transparent to infrared radiation, so infrared radiation from the warm surface is absorbed by the atmosphere and cannot escape back into space. That traps heat and makes Earth warmer.