Hydrogen because it only has one valence electron I believe.
Answer:

Explanation:
Straight wings are dominant over curved wings
Let Straight wings : H
curved wings : t
smooth eyes are dominant to sparkling eyes
let smooth eyes = H
spark ling eyes = t
tan body is dominant to ebony body color.
Again; Let tan body color be H
Let ebony color be t
If flies that are heterozygous for all three traits are crossed;
we have HtHtHt × HtHtHt
Then the selected trihybrid traits for the cross will be (HHH,HHt, HtH, Htt, tHH, tHt, ttH, ttt)
We will realize that from the punnet square in the diagram below, the proportion of the offspring would you expect to be heterozygous for all three traits (i.e HtHtHt) is asterisk in the punnet square and will be 
= 
Fossils can give information about past environmental conditions by showing the type of animal they belonged to. If a scientist found a whale fossil in a desert, he/she could assume that the desert was once an ocean as whales only live in oceans. If someone found a fossil of a lizard that inhabited trees, in the middle of the ocean, then he/she could assume that the ocean didn't exist at one point and instead, there might have been a forest in it's place.
Hope this helps!
What did you say about the cats in your room haha