What is the color change of the litmus paper for each of these cases?

This question relates the change in color of the litmus paper when it is dipped in solutions of different pH values. In general, a blue litmus paper turns red when dipped in acidic solution and a red litmus paper turns blue when dipped in a basic or alkaline solution. The color of the neutral litmus paper is purple. 

Note that the color change takes place between a pH of 4.5 and 8.3, thus, the paper remains blue above a pH of 8.3 and red, below a pH of 4.5.

Also, remember that pH is related to the hydrogen ion concentration of a solution as:

`pH = -log_10[H^+]`

For these cases, where the hydrogen concentration is given, convert them to pH.

For case A: 

pH = `-log_10[1.3 xx 10^(-9)]`

or, pH = 8.9

Thus, the red litmus will turn blue, while blue litmus paper will show no change.

Similarly, for case C: pH = -log(1 x 10^-7) = 7. 

The pH is around neutral and hence the red litmus as well as the blue litmus paper will exhibit no change in color.

Similarly, for solutions E and F, pH = 7 and hence the litmus papers will show no change of color.

For case D, pH =4.5, hence red litmus will have no change, while blue litmus paper will turn red.

Similarly, all other cases can also be solved.

Hope this helps.