Answer 1

You could do it with javascript, but...

the use of radio buttons is that exactly 1 MUST be selected and

the use of checkboxes is that MORE THAN 1 CAN be selected...

Can you elaborate why you want to achieve this behavior?

Answer 2

Maybe something like this:

For radio buttons: On click of the item, revert the checked status if it is checked.

For checkboxes: On change count the number of checked boxes in the group and set an upper limit. Of the limit is reached, disable unchecked checkboxes until the number is below the limit
https://stackoverflow.com/questions/19001844/how-to-limit-the-number-of-selected-checkboxes#19001936

Answer 3

And in your quiz, one should select only one item and you want to score "blank" questions differently?

Answer 4

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month
week
date
time
password
color
file
email
tel
text
url