How many non-zeros samples in convolution

1. Can convolution of two non zero signals be zero?
2. Can convolution be zero?
3. How many signals are there in linear convolution?

Can convolution of two non zero signals be zero?

It is easy to see that in case of a convolution, the result will be zero for all values of n.

Can convolution be zero?

If at all frequencies at least one of the signals is zero-valued in frequency domain, then the convolution of the two signals will be zero-valued at all frequencies, and at all times.

How many signals are there in linear convolution?

In linear systems, convolution is used to describe the relationship between three signals of interest: the input signal, the impulse response, and the output signal.