<em>"Who"</em> (or <em>whom</em>) is a pronoun, and is used as the subject or object of a verb to show which person you are referring to.

"Which" is a pronoun, and is used as the subject or object of a verb to show what thing or things you are referring to.

"That"<em> </em>is a pronoun, and is used as the subject or object of a verb to show which person or thing you are referring to. It can sometimes be omitted. <em>
The girl who was hungry.
The boy whom I talked to. </em><em>
The dog that wagged its tail.
The software ( that) I wrote.
The company, which / that hired me. </em>

<em>Loose </em> is an adjective. If something isn't fixed properly or it doesn't fit, because it's too large, it's loose.

<em>For example:-</em>

<em>My headphones weren't working, because a wire was loose.</em>

Lose is a verb that means to no longer possess something because you do not know where it is, or because it has been taken away from you.

For example:

A lot of people will lose their job if there is a recession.

<em>Lay</em> is an irregular transitive verb (lay / laid/ laid - laying). It needs a direct object. It means to put something or someone down (often in a horizontal postion).

For example: <em>"Lay your head on the pillow." </em>

<em>Lie </em> is an irregular intransitive verb (lie / lay / lain - lying). It does not take a direct object. It means to rest in a horizontal position¹ or to be located somewhere².

For example: <em>"If you are tired lie here and have a rest."¹
"Nottingham lies in the Midlands."²</em>

<em>Homework </em>(noun) - refers to tasks assigned to students by teachers to be completed mostly outside of class, and derives its name from the fact that most students do the majority of such work at home.

For example: <em>"A lot of students in the UK get too much homework." </em>

<em>Housework </em>(noun) - refers to domestic household chores such as cleaning and cooking.

<em>For example: "I never seem to have enough time to do the housework. There's always something that needs dusting or polishing</em>

Everyone gets this wrong - including native speakers. The general rule is to use fewer for things you can count (individually), and less for things you can only measure

<em>For example: </em>

<em>There were fewer days below freezing last winter. </em>(Days can be counted.)

<em>I drink less coffee than she does.</em> (Coffee cannot be counted individually it has to be measured).

!Note - "Less" has to do with how much. "Fewer" has to do with how many.