Which one of the following is an example of a redox reaction?

a. mixing sodium hydroxide with hydrochloric acid to form table salt and water
b. rust on a bicycle
c. deposits of solid magnesium and calcium oxides in pipes
d. using baking soda and vinegar in a cookie recipe

The answer is that they are composed mostly of liquid water.

Jenny and fred both play a long note on their trombones. a stationary observer hears the sound increasing and decreasing repeatedly in loudness. which of these must be true? the sound waves from the two trombones have slightly different frequencies.the sound waves from the two trombones have the same frequency.the sound waves from the two trombones have slightly different amplitudes.the sound waves from the two trombones have the same wavelength.the sound waves from the two trombones have slightly different velocities.  lolthe answer is          the sound waves from the two trombones have slightly different frequencies.