Y <br/> and some other tags dosent have closing tags

Answer 1

it's not true html is based on XML so you can write <br />
as
<br></br>
it should also works, but the br tag doesn't have child so it is best to use short hand. instead of writing like this
<TAG></TAG>
you can write like this
<TAG />

Answer 2

Thanks

Answer 3

because <br/> is a breakpoint to not form a paragraph like with <p> which creates a paragraph so you can put <br/> to split certain words apart