The iron we commonly find in our surroundings came from: A) ...

[Kthamas]

The iron we commonly find in our surroundings came from:
 
  A) the iron core of a massive star which exploded as a type I supernova.
  B) planetary nebulae.
  C) jets ejected by a rapidly spinning pulsar.
  D) material ejected by a nova explosion.
  E) decay of nickel 56 and cobalt 56 in a supernova remnant.

Question 2

According to Copernicus, the retrograde motion for Mars must occur:
 
  A) at inferior conjunction, when Mars laps the Earth and passes between us and the Sun.
  B) at superior conjunction, when Mars lies on the far side of the Sun.
  C) at quadrature, when Mars lies exactly 90 degrees east or west of the Sun.
  D) at greatest elongation, when Mars can get up to 47 degrees from the Sun.
  E) at opposition, when the Earth overtakes Mars and passes between Mars and the Sun.

[xthemafja]

Answer to Question 1

E

Answer to Question 2

E

[Kthamas]

Thanks for the timely response, appreciate it

[bigcheese9]

Great answer, keep it coming