It is a heterogeneous mixture because you can distinguish between the different colored marbles. The mixture is not the same throughout.
It is an element.
Homogeneous mixture
Vinegar is a homogeneous mixture.
This is a heterogeneous mixture.
Cheerios is a heterogeneous mixture.
heterogeneous
compound and element
compound
It is an element.
heterogeneous
Concrete is a heterogeneous mixture.
it is a heterogeneous
Vinegar is a homogeneous mixture.
Homogeneous mixture
This is a heterogeneous mixture.
Cheerios is a heterogeneous mixture.
heterogeneous