Given that there are 40 questions, you could try a funky approach to ensuring that all have been selected.You could create an array (programtically find the number of questions and then create the array of numbers) leading to an array with all 40 numbers (note that arrays are zero indexed - meaning the first value may be "1" but it will be indexed as "0").
The difficulty with radio buttons is that there are at least two and usually more fields that need to be placed on the form, related together and tested as one group.
Provided that you use the correct naming conventions and layout for your buttons, you will not have any trouble.
The creation of multiple groups of radio buttons for the one form is also straightforward.
All you need to do is to provide the second group of radio buttons with a different name to that used for the first group.