Which of the following statements is/are TRUE for undirected graphs?
P: Number of odd degree vertices is even.
Q: Sum of degrees of all vertices is even.

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

$$K4$$ and $$Q3$$ are graphs with the following structures.

Which one of the following statements is TRUE in relation to these graphs?

Let $$G$$ $$\,\,\,\,\, = \,\,\,\left( {V,\,\,\,\,\,E} \right)$$ be a graph. Define $$\xi \left( G \right) = \sum\limits_d {{i_d} \times } {\mkern 1mu} d,$$ where $${{i_d}}$$ is the number of vertices of degree $$d$$ in $$G$$. If $$S$$ and $$T$$ are two different trees with $$\xi \left( S \right) = \xi \left( T \right)$$, then