The molecular formula for compound is 
mass of compound is 0.670 g.
To calculate number of atoms first calculate number of moles in the compound as follows:
Molar mass of is 283.886 g/mol, thus,
Thus, number of mole of is 0.00236 mol.
From the molecular formula 1 mole of has 2 mol of P (phosphorus) and 5 mol of O (oxygen).
Thus, number of moles of P and O in 0.00236 mol of will be:
Similarly,
Now, in 1 mol of an element there are 
atoms.
Number of atoms of P will be:
Similarly, number of atoms of O will be:
Total number of atoms will be sum of number of atoms of P and O:
Therefore, total number of atoms in will be 
.
Answer:
0.3428 g/mL is the concentration that student will write in her notebook.
Explanation:
Mass of the empty graduated cylinder, w = 2.2 g
Mass of sodium thiosulfate and graduated cylinder ,w'= 19.440 g
Mass of sodium thiosulfate : W
= w' - w = 19.440 g - 2.2 g = 17.24 g
Volume of the solution after adding water to the graduate cylinder with sodium thiosulfate = V
V = 50.29 mL
According to question :
Concentration of the solution :
0.3428 g/mL is the concentration that student will write in her notebook.
hope you can read it. hope it's right too :).
All the best.
The oxidation state of hydrogen gas is 0 and oxidation state of hydrogen cation is +1.
There’s an increase in oxidation number therefore it’s an oxidation reaction.
Oxidation reactions give out electrons. The masses and charges on both sides should be balanced
Half reaction is
H2 —> 2H+ +2e
