1. I think a drum would be the easiest instrument to explain. You can vary the pitch and loudness by hitting it with different intensities or at different points or angles.
PS. I'm not talking about a drumset. I'm talking about an ordinary drum.
2. Different types of instruments sound different even though they play the same notes because they use different mechanisms for producing sound.
Answer: a) speed = 3.45 × 10^-2 m/s
b) speed = 1.38 × 10^-1 m/s
Explanation: shown in the attachment
I believe it is lithosphere
The independent variable is the different amount of repellent each person is given. This is because it does not depend on any variable. The dependent variable is what they are measuring, which would be the number of bites on each volunteer.
I hope this helps! :)