0.5 moles, though not a verified answer hope it helps! :D
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:
The grating spacing is 
Explanation:
From the question we are told that
The wavelength is 
The angle is 
The order of the spectrum is 
Generally in grating grating the condition for maxima to occur is
where d is the grating spacing
making d the subject of the formula
Substituting values
The answer would be a) body-centered cubic.
