Answer:
Fig 3 is a mixture
Explanation:
Fig 1 has just one kind of atoms.
fig 2 shows 2 atoms of the same kind bonded together (compound)
fig 4 shows atoms of 2 different kinds bonded together (compound)
only in fig 3 we see uneven distribution of two kinds of atoms. By definition a mixture contains two or more kind of substances randomly arranged. So fig 3 shows arrangement of mixture
