Analysis of the solar spectrum shows that the Sun is mostly _____.

Analysis of the solar spectrum shows that the Sun is mostly _____.
 
  A) helium
  B) hydrogen
  C) fluorine
  D) nitrogen

Question 2

The Perseid meteor shower is named after a(n) _____.
 
  A) comet
  B) asteroid
  C) constellation
  D) star

Question 3

The Perseid meteor shower occurs each year in _____.
 
  A) May
  B) June
  C) July
  D) August

Question 4

The half-life of a radioactive element is the time it takes for:
 
  A) half of the radioactive atoms to double themselves.
  B) half of the radioactive atoms to decay into isotopes.
  C) the radioactive atoms to increase by half of its initial quantity.
  D) the radioactive atoms to increase to 1.5 times of its initial quantity.