HTML CSS back to the basics

We all know HTML and CSS but it is always better to look back to the basics and re-assure we know the basic. Here are some questions related to HTML that I have found a bit difficult but good to learn again.

• Which two elements are used to mark-up subscript and superscript text?

• Which markup is correct in the below list?
  

<date time="2025-10-08">October 8, 2025</date>

<date>October 8, 2025</date>

<datetime time="2025-10-08">October 8, 2025</datetime>

<time datetime="2025-10-08">October 8, 2025</time>

• Which code produces the output shown in the image below?

2<sub><small><small> 5</small></small></sub><sup>8</sup>

2<sup><small><small> 8</small></small></sup><sub>5</sub>

2<sup><small><small> 5</small></small></sup><sub>8</sub>

• Which markup is correct in below list?

<date time="2025-10-08">October 8, 2025</date>```

October 8, 2025```

<time datetime="2025-10-08">October 8, 2025</time>

• Why would you want to use the w specification in srcset instead of the x specification?

• Which one is pseudo class and which one is pseudo element in the below code ?
  

p:first-of-type {

}
p::first-letter {

}

• What is margin collapsing?

• When a float needs to be cleared using the parent element, what “display” value should be used?

• "flex" is the shorthand property for which three longhand properties?