In preorder traversal of a binary tree the second step is ____________

Breadth First Search traversal of a binary tree finds its application in __________

The decision tree structure begins at a node called the _____.

In any undirected graph,the sum of degrees of all nodes

Let G be a simple undirected planar graph on 10 vertices with 15edges. If G is a connected graph, then the number of bounded faces in any embedding of G on the plane is equal to