Question

1. which is a heterogeneous mixture?

a mug of hot cocoa
a gallon of milk
a glass of tap water
a jar of mixed nuts

Explanation:

A heterogeneous mixture has visibly different substances or phases. Hot cocoa is a homogeneous mixture (uniform). Milk is a colloid (uniform). Tap water (if pure) is a compound; if with impurities, still appears uniform. Mixed nuts have different types of nuts (visibly distinct), so it's heterogeneous.

Answer:

a jar of mixed nuts