Answer:
Weigh 4.5 grams of sodium hydroxide and add it to the dry volumetric flask of 450 mL followed by small amount of water to dissolve all the NaOH .After this add the water upto tye mark of 450 mL.
Explanation:
Molarity of the solution is the moles of compound in 1 Liter solutions.

Mass of NaOH = x
Molar mass of NaOH = 40 g/mol
Volume of the NaOH solution = 450 mL =- 0.450 L ( 1 ml = 0.450 L)
Molarity of the solution of NaOH = 0.250 M


Solving for x:
x = 4.5 g
Weigh 4.5 grams of sodium hydroxide and add it to the dry volumetric flask of 450 mL followed by small amount of water to dissolve all the NaOH .After this add the water upto tye mark of 450 mL.
Answer:
1 dihydrogen reacts with 1 chlorine to form two hydrogen chloride (edit: hydrogen chloride is also referred to as hydrochloric acid)
First you find out how much each element has
Fe=1 * 2 Fe=1
Cl=2 *3 Cl=3 *2
now we multiply each so we can balance each side.
So now we get our balanced equation
2 Fe + 3 Cl2 = 2 FeCl<span>3</span>
The answer to that is mass and chemical