Answer: The space occupied by the gas at 400 torr and
is 250 mL.
Explanation:
Given:
= 250 mL,
= 800 torr, 
,
= 400 torr, 
Formula used is as follows.

Substitute the values into above formula as follows.

Thus, we can conclude that space occupied by the gas at 400 torr and
is 250 mL.
<h2>In the name, iron(III) oxide, the (III) represents: D) the electrical charge of iron</h2><h2>
Explanation:</h2>
To attain stability the chemical bond is formed .
Chemical bond
It is a kind of linkage that binds one atom with the other .
The atoms do so in order to attain stable noble gas configuration .
To form chemical bond they either:
Loose electrons : when atoms loose electrons they acquire positive charge which is equal to the number of electrons lost .
Gain electrons: After gaining electrons they acquire negative charge which is equal to the number of electrons gained by an atom.
share electrons : With sharing no charges are develop .
<em>In the above asked question when iron combines with oxygen it forms iron oxide : where iron looses 3 electrons and oxygen gains 2 electrons .That is the reason ,III here represents the electrical charge of iron</em>
It is 4/10 of moles is this ane halp?