State two smaller units of volume. How are they related to the S.I. unit?

The two smaller units of volume are cubic centimetre (cm³), cubic decimetre (dm³).

1 m³ = 1 m x 1 m x 1 m
= 100 cm x 100 cm x 100 cm
= 1000000 cm³
= 10⁶ cm³

So, 1 m³ = 10⁶ cm³

1 m³ = 1 m x 1 m x 1 m
= 10 dm x 10 dm x 10 dm
= 1000 dm³
= 10³ dm³

So, 1 m³ = 10³ dm³