Saya minta tolong gimana jalan nya

P total = P H₂ + P Ne
40 = 12 + P Ne
P Ne = 40 - 12 = 28 atm

n H₂ = (gr H₂)/(Mr H₂)
= 6/(2 . 1) = 3 mol

n Ne = (gr Ne)/(Ar Ne)
= gr Ne/20 mol

(P H₂)/(P Ne) = (n H₂)/(n Ne)
(P H₂)/(P Ne) = 3/(gr Ne/20) 
12/28 = 60/gr Ne
3/7 = 60/gr Ne
7 . 60 = 3 . gr Ne
gr Ne = 420/3 = 140 gr

massa gas total dalam tabung 
= gr H₂ + gr Ne
= 6 + 140
= 146 gr