The lowest tone to resonate in an open pipe of length L is 200 Hz what frequencies will not the same a 400Hz b 600Hz c 800Hz d 900Hz?

The lowest tone to resonate in an open pipe of length L is 200 Hz. This means that the first harmonic of the pipe is 200 Hz. The frequencies that will not resonate in the pipe are those that are not harmonics of 200 Hz.

The harmonics of 200 Hz are:

$$200 \text{ Hz, } 400 \text{ Hz, } 600 \text{ Hz, } 800 \text{ Hz, } 1000 \text{ Hz, etc.}$$

Therefore, the frequencies that will not resonate in the pipe are:

$$300 \text{ Hz, } 500 \text{ Hz, } 700 \text{ Hz, } 900 \text{ Hz, etc.}$$

So, the correct answer is d) 900 Hz.