The traditional calcium atom has twenty protons and twenty electrons making it neutral.
The calcium in the pic is a calcium ion so the number of protons and electrons are not equivalent.
Since it's 2+ that means the ion is positively charged and for that to happen electrons are away.
So 20-2=18
There are 18 electrons
22.4L
of any gas contains 1 mol of that gas.
50.75g/10L*22.4L/1 mol= 113.68g/mol- this is the mole weight of your gas
1 mol/113.68g*129.3g=1.137403 mol
Set up a ratio
1.137403mol/x L=1 mol/22.4 L
X=25.477827L, or with sig figs, x=25.5L
Answer:

⇒ We have Na2O + H2O --> NaOH. We have 2 sodiums and 2 oxygens and 2 hydrogens on the left side, but only one of each on the right side.
Sodium Oxide + Water → Sodium Hydroxide
⇒ Na2O + H2O → 2NaOH .
Sodium oxide is used in ceramics and glasses. Sodium oxide reacts exothermically with cold water to produce sodium hydroxide solution.