If you were presented with 2 L of a 2 M sucrose stock solution, how many grams of sugar would be in a 100 mL aliquot?

You need to know the formula (= molecular) weight of sucrose =342 grams per mole
& you need to understand the concept of a mole.

1 L of a 1 M solution will contain 343 gm of sucrose
... a 2 M solution will have twice as much ( 686 gm in a liter)

The volume (2 L) doesn't matter. It's just an attempt to make the question appear harder.

But the 100 mL matters, right?

Right, 100 ml is 1/10 of a liter
So, if you have 343 gm in 1 liter how much do you have in 1/10 of a liter

OK?