What is the default size for changing the width and height utilities of an element?

 . Which class indicates new or unread items?
 

 Which class is used to separate links in dropdown menu? 

Which of the folloeing class is used to use link as button?

   What lines up the terms and descriptions in <dl> element side by side?
 

What does Bootstrap automatically use to adjust pages for various screen sizes?

How to force the next columns to break to a new line in a flexbox layout?

For which class(es) does .mx-auto work?

What is the correct order to load the following scripts in a web page?

Explain the use of the meta tag below.

<meta name="viewport" content="width=device-width, initial-scale=1">