Question One
It's more a question of unscrambling what is there. The answer is correct.
If you look at your periodic table, there is such an element as Na which I suspect might be the problem.
It has an atomic mass of 23. It's atomic number is 11 which means it is the 11th member (by mass) on the periodic table. The other 2 are oxygen and hydrogen. So Oxygen has an atomic mass of 16 and Hydrogen has an atomic mass of 1.
Oxygen is number 8 on the periodic table and hydrogen is number 1.
Molecular Mass
Na = 23
O = 16
H = 1
Total 40, just as the answer key says. I've probably given you more than you wanted to know, but if you still have trouble, leave a note.
Answer:
1. Equality
<u><em>Hope this helps :)</em></u>
<em><u>Pls brainliest...</u></em>
The mass percent of oxygen in Nickel(
)sulfate is 
percent.
At first, we look up the atomic masses for the element from the periodic table.
The atomic masses are found to be:
Next, we determine how many grams of each element are present in one mole of 
The mass of one mole is:
So, The mass percent of oxygen 
percent.
To learn more about Mass percent, refer to:
Answer:
halving, the mass of planet X and halving the distance between the planets
of Ni
of S
of O