In the three-dimensional structure of methane, ch4, the hydrogen atoms attached to a carbon atom are aligned at

Corner of tetrahedral structure

Explanation:

In three dimension methane has tetrahedral structure in which central atom is carbon which has four valance electron.

Each valence electron of carbon is shared by hydrogen atom as there are 4 valence electron in so there will be 4 hydrogen atom

And each hydrogen atom is aligned at the corner of tetrahedral structure of