For checking a regular expression in input fields of HTML forms which attribute

For checking a regular expression in input fields of HTML forms which attribute is used?

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1) All elements are identified by their __________ and are marked up using either start tags and end tags or self-closing tags

2) What will happen if height and width of video are not set while video loads?

3) The __________ attribute effectively renders the iframe as an inline include, which allows the parent document’s CSS to affect the contents of the iframe

4) Which of the following defines a group of related options in a drop-down list.

5) In HTML Audio/Video DOM, __________ sets or returns whether the audio/video should start over again when finished.