6.02*10^23 is Avagadro's number representing the number of molecules per mole of substance.
(4.99 g) / (3.65 g/mL) = 1.37 mL
The answer to your question is 1.37ml.
2..............................................
You can use P1V1/T1 = P2V2/T2 but since pressure is constant is becomes V1/T1=V2/T2
V1=0.5 L
T1=203 K
T2=273 K
V2=unknown
0.5L/203 = V2/273
V2= 0.67 L so C
Hope this helps :)
