Answer to the question no 1:
A binary tree is a tree data structure in which each node has at most two children, which are referred to as the left child and the right child.
Answer to the question no 2:
In a full binary tree all nodes have either 0 or 2 children.
A complete binary tree is a binary tree in which every level, except possibly the last, is completely filled, and all nodes are as far left as possible.This means that all nodes have two children except the nodes at the lowest two levels. At the lowest level the nodes have (by definition) zero children, and at the level above that nodes can have 0, 1 or 2 children.