multiple-response categorical variables - what is "n", chi-squared


I am doing independence checks (chi-squared tests) on two variables. One of the variables is of the interval nature and the other is a multiple-response categorical variable.

Couple of questions:

1. What is "n"? The number of respondents, or the number of responses, or something else?

2. Can I still use the chi-squared test? If so, do I have to make any adjustments?