P-V and T-S diagrams

Question

What is meant by free expansion process and how does it differ from throttling process? One kilogram of a gas having pressure P₁ and temperature T₁ is enclosed in an insulated box of volume V₁. It is allowed to expand freely till its volume increases to V₂ = 2 V₁. Show the process on P-V and T-S diagrams and determine Q, $\Delta$V, W and $\Delta$S for the free expansion process. Comment on the results.