To avoid listing every checkbox explicitly, just work out how to define the range where all the checkboxes sit. For instance, putting one question's checkboxes AND the clear button into a table cell will allow you to reuse the same code for each question.
Code:
Private Sub ClearQ_Click()
Dim aFF As FormField
For Each aFF In Selection.Range.Cells(1).Range.FormFields
If aFF.Type = wdFieldFormCheckBox Then aFF.Result = False
Next aFF
End Sub