(Blank)
100

The (affect or effect) of the medication was noticeable."

Effect because it means a result of something rather than affect which is the verb of influence of impact 
200

("Who's or whose) going to the party?"

Who's because it is a contraction of who has 

300

The girl (threw or through) her ball in the water.

Threw because it is a verb 

400

I was going down the (isle or aisle) to find the flour for my cake. 

Aisle because it is talking about going down a row not to a piece of land

500

Since my mom was the only one with a sense of direction, she (Led or lead) the way.

Led because it means to show the way rather than lead as a toxic material

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