B)
how many g of o2 are needed to produce 6.0 mol of h2o?

Mass of oxygen that will be required to produce 6  mole of water is 96g .

Explanation:

Mass of oxygen = ?

Atomic mass of oxygen is =16g

Molecular mass of O₂= 32 g

Now, according to question statement we need to calculate oxygen needed to produce 6 mol of water .

In 1 mol of water  ,there is O₂/2 is present or we can say that 1 oxygen atom is present .

We also know that ,

1 mol of water has = 1 mole of oxygen

Therefore ,

6 moles of water will have 6 moles of oxygen atom

Mass of 6 moles of oxygen atom can be calculated as :

Mole =given mass/atomic mass

6=X /16

X = 16 x 6

=96g

c, liquids evaporate, creating a gas