You can rewrite the ideal gas as n/V=P/RT to find the moles per liter. 10^(-15)atm/(0.08206Latm/molK)(276K)=4.415x10^(-17)mol/L
since we know that one cm³ equals 1mL which equals .001L you can turn the mol/L into mol/cm³. (4.415x10^-17mol/L)x(1L/1000mL)=4.415x10^(-20)mol/cm³
than multiply that number by Avogadro's number to find the number of molecule in that unit volume. (4.415x10^(-20)mol/cm³)x(6.02x10^23molecules/mole) =2.658x10^4molecules/cm³
The zero to the left of a decimal value less than 1 is not significant.All trailing zeros that are placeholders are not significant.Zeros between non-zero numbers are significant.All non-zero numbers are significant.
