Volume of a substance can be determined by dividing mass of the substance by its density.
That can be mathematical shown as:
Density=Mass/Volume
So, Volume=Mass/Density
Here mass of the substance given as 24.60 g
Whereas density of the substance is 2.70 g/mL
So,
Volume=Mass/Density
=24.6/2.7
=9.1 mL
So volume of the substance is 9.1 mL.
<span>PV/T = P'V'/T'
660 x 1.00/295.2 = P' x 1.00/317.8
P'=710.5 torr</span>
They all look like there decaying and was left out or sat inside too long