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If we are talking about one single carbon atom, then 4 hydrogen atoms can be bonded to a carbon atom, because there is 4 electrons in the valence shell, and a valence shell needs 8 electrons in total, which causes the carbon to have 4 open bonds. A hydrogen has only one electron in its valence shell of 2, and needs one more to complete it. So, each hydrogen connects to 1 of 4 bonds on the carbon to complete the valence electron.
Fun fact, CH4 is methane.
Answer:
Box 1: AA
Box 2: Aa
Box 3: AA
Explanation:
In order to figure out the pedigree, you first have to do a punnet square- kind of like cross-multiplying. EX: For the first box: Aa x AA
For box one, we know that it is Aa, and not AA, because box 2 has to be AA.
We know that because Aa X Aa would give us some "aa" offspring which we do not see in the last generation (see 2nd pic). The only way to get no "aa" offspring is to have an AA X Aa cross.