Answer:
1st Blank: <em>1 Co</em>
2nd Blank:<em> 2 Na2S</em>
3rd Blank:<em> 4 Na</em>
4th Blank:<em> 1 CoS2</em>
Explanation:
<em>Trust me</em>
your answer is c. two atoms of oxygen.
The reaction between hydrogen and oxygen to form water is given as:

The balanced reaction is:

According to the balanced reaction,
4 g of hydrogen (
) reacts with 32 g of oxygen (
).
So, oxygen reacted with 29.4 g of hydrogen is:

Hence, the mass of oxygen that is reacted with 29.4 g of hydrogen is 235.2 g.