Their proton and electron numbers are same
So the first thing we must do is write a balanced equation for the reaction and we know the equation is balnced when all the species on the RHS is equal to the species on the LHS
2NaOH + H₂SO₄ → Na₂SO₄<span>
+ 2H₂O</span>
So now it's time to identify what reactant you know the most for from the question (volume & conc. of H₂SO₄) and use that info to find the unknown (conc. of NaOH)
If 1000 ml of H₂SO₄ contain 0.750 mol [0.750 M is the amount of moles in
1 L (1000 ml)]
then let 15 ml of H₂SO₄ contain x mol [15 ml is the amount of the acid that took part in the reaction]
⇒
x =
= 0.01125 molMole ratio of NaOH to H₂SO₄ can be obtained from the balanced equation
0
2NaOH +
1H₂SO₄ → Na₂SO₄ + 2H₂O
mole ratio of NaOH to H₂SO₄ is 2 : 1∴ if mole of of H₂SO₄ = 0.01125 mol then moles of NaOH = (0.01125 mol) × 2 = 0.0225 molIf 17.5 ml of NaOH contain 0.0225 mol [this was given in the question]
then let 1000 ml of NaOH contain x⇒ x =
= 1.286 mol∴ concentration of NaOH is 1.286 mol/L
Answer:
0.171 grams of oxygen combined with the metal.
Explanation:

Mass of magnesium oxide produced = 0.421 g
Mass of magnesium metal used = 0.250 g
Suppose reaction completely converts the magnesium into magnesium oxide.
Mass of oxygen combined with magnesium = m
0.421 g = 0.250 g + m
m = 0.421 g - 0.250 g = 0.171 g
0.171 grams of oxygen combined with the metal.
100 mm = 100/1000= .1 meters
1cm = 1/100 = .01m
10 decimeters = 10/10 = 1 meter
.0001 km = .0001*1000 = .1 meter