Discuss the below:
1. Is the following a graph? Explain.
![757_Graph.jpg](https://secure.tutorsglobe.com/CMSImages/757_Graph.jpg)
2. The vertices of the following graph are to be colored so that the adjacent vertices will not have the same color. Find the chromatic number of the following graph.
![1352_Vertices of graph.jpg](https://secure.tutorsglobe.com/CMSImages/1352_Vertices of graph.jpg)
3. What is the minimum number of colors required for the following graph so that the adjacent regions with a common boundary other than a point are to have different colors?
![1867_Regions.jpg](https://secure.tutorsglobe.com/CMSImages/1867_Regions.jpg)