Can you please help with question 1 and 4

i) 24.305 u

iv) The number of protons determines an element's atomic number and is used to distinguish one element from another.

1) 24

2)protons

Explanation:

1) magnesium Ar

2) atomic number

There's no such thing as a heterogeneous or a homogeneous compound, since compounds are a pure substance.

Assuming that you're talking about heterogeneous and homogeneous mixtures, then a heterogeneous mixture is not evenly mixed well (imagine a taco. A homogeneous mixture is molecularly evenly mixed (imagine a smoothie).