1)Root - top node of a structureChild - nodes lower then another in the hierarchyLeaf - a node at the end of the treeParent - a node higher just above the current nodeAncestor - a node somewhere above the current in the treeSub-tree - tree inside the main tree2) You need 17 levels to store 100,000 nodes.3) a) 1-min and 15 max b) 7 min and 7 max8) It counts the number of leaves.public class exercises{ public boolean isLeaf(TreeNode node) { return node.getLeft() == null && node.getRight() == null; } public int sumTree(TreeNode root) { if(root == null) return 0; int sum = 0; sum += (Integer)root.getValue(); sum += sumTree(root.getLeft()); sum += sumTree(root.getRight()); return sum; } public int countPaths(TreeNode root) { int sum = 0; if(root.getLeft() != null) { sum++; sum += countPaths(root.getLeft()); } if(root.getRight() != null) { sum++; sum += countPaths(root.getRight()); } return sum; } public int depth(TreeNode root) { if(root == null) return 0; int d = 1; return Math.max(d + depth(root.getLeft()), d + depth(root.getRight())); }}