How much water can be produced from the complete reaction of 3.84 l of oxygen gas, at stp, with hydrogen gas? answer in units of g?

First, write a balanced chemical equation:

2H2(g) + O2(g) --> 2H2O(l)

We are given that oxygen has a volume of 3.84L, so we need to use the formula n = V / MV 

As mentioned, at stp, so MV= 24.79

n = 3.84 / 24.79
   = 0.1549...

The ratio of oxygen to water is 1:2, therefore we need to multiply the moles found by 2 to gain the moles of water,

n = 0.1549... x 2
   = 0.3098...

Use the formula n = m / M, where m is mass and M is molar mass

0.3098.. = m / (2(1.008) + 2(16))
m = 0.3098... x (2(1.008) + 2(16))
    = 10.538...

Therefore, 10.54g of water is produced (2 d.p)

HOPE THIS HELPED!