Hi Ratan,
Please see enclosed your file.
I have used Form Control ComboBox to make the chart dynamic in place of your data validation.
Also, have a look at Sheet "Multiple Q" which i have inserted additionally. In this you can choose any combination of Q to plot on graph (which is not possible in your sheet where only one Q is plotted on graph). You can certainly change the graph type or other details as per your requirement. If you do not have any use for it you can simply delete the Sheet "Multiple Q".
Thanks.