The particles that make up the atomic nucleus of all atoms are both protons and neutrons.
109.5
tetrahedral shape:
number of electron pair = 4,
number of bonded pair = 4,
number of lone pair = 0.
I would think it is a heterogeneous mixture since it can't be an element since there are more than one type of atom, it can't be a compound since the leaves are not bonded together, and it can not be a homogeneous mixture since the leaves don't all blended together (the pile is not uniform) and you can distinguish all the different parts of the mixture. It can be considered a heterogeneous mixture since the leaves are mixed together (along with other things like dirt) in a non-uniform way so that you can point out the parts of the mixture and it does not look like one thing.
I hope this helps. Let me know in the comments if anything is unclear.
The force that accelerates objects towards Earth is gravity.
