Google Forms - Require a Question to Be Answered
If you prefer a short video, here is one on both creating a new question and requiring it to be answered.
To require a question be answered:
While in edit mode of your form, click on the question so it is also in edit mode. Look for the Required option in the lower right of the question -
Click on the slider to make the question required (the slider will change to a color in your theme)-
When you are not editing the question, a red asterisk will be displayed next to the question showing it is a required question -