The substance which does not expand on going from liquid state to solid state is

Understanding the Question:
This question asks us which of the given substances does NOT get bigger (expand) when it changes from a liquid to a solid.

Explanation of Options:
Option A: Water - When water freezes into ice, it actually expands. This is why ice floats and why pipes can burst in winter.
Option B: Cast-iron - Cast iron also expands when it solidifies. This property is useful in casting.
Option C: Aluminium - Aluminium contracts (gets smaller) when it solidifies. This is the opposite of expanding.
Option D: Type metal - Type metal expands when it solidifies allowing it to fill intricate molds.

Why the Answer is Aluminium:
Aluminium is the only substance on the list that contracts instead of expanding when it changes from liquid to solid.

Therefore, the correct answer is C: aluminium