The molecular weight of a gas that has a density of 8.6g/L at STP is?

The simplest way is to multiply by 22.4L/mole

6.70g/L x 22.4L/mole = 150.g/mole

Another way is to substitute m/M (mass/molarmass) for n into PV = nRT.

PV = mRT/M

M = mRT/PV

m = 6.70g, V = 1L, pick compatible values for STP and R.

Explanation:

percent abundance for cu-63 can be shown as:

63 x + 65 (1-x) = 62.9296

65 - 62.9296 = 2 x

x = 1.035

thus, percent abundance for cu-63 is 1.035

percent abundance for cu-65 can be shown as:

63 x + 65 (1-x) = 64.9278

65 - 64.9278 = 2 x

x = 0.0361

thus, percent abundance for cu-63 is 0.0361

the mass spectrum of cu-63 showing the intense peak as, this isotope is found in nature more abundantly around 92.38 % in comparison to cu-65 which is found 62.58 % naturally