2 <span>KOH +1 H3AsO4 →1 K2HAsO4 + 2 H2O</span>
Shape
A gas is shapeless all other things being equal. It will, if put in a container, occupy every part of the container.
A liquid could also be thought of shapeless. If put in a container, it need not occupy the entire container. It will occupy as much as its calculated volume will permit it to occupy.
A solid will only occupy its original shape.
Volume
A gas will occupy whatever container it is put in within limits. You cannot put a 72 mols of gas in a mm^3 container without some amazing ability to apply a lot of pressure.
A liquid will occupy a volume determined by its density and mass. In general liquids cannot be compressed.
Whatever volume a solid has to start with, it will retain that volume all other things being equal.
This is actually very hard to describe.
Answer:

Explanation:
The reaction of gaseous sulfur dioxide and oxygen to form SO3 (g) is:
2SO₂(g) + O₂(g) ⇄ 2SO₃(g)
Kp is defined as the ratio of pressure of products and pressure of reactants:

I hope it helps!