Chemistry GCSE AQA - Need help on a question

The student found that 15.5 cm3 of 0.500 mol/dm3 dilute sulfuric acid completely reacted with 25.0 cm3 of potassium hydroxide solution.
The equation for the reaction is:
2KOH + H2SO4 → K2SO4 + 2H2O
Calculate the concentration of the potassium hydroxide solution in mol/dm3 and in g/dm3
Relative atomic masses (Ar): H = 1 O = 16 K = 39.
My specific question is when calculating the Mr of a specific compound do you count the coefficient? Here, do you count the 2 in front of KOH?
Can you please help solve this question step by step and illustrate?

The student found that 15.5 cm3 of 0.500 mol/dm3 dilute sulfuric acid completely reacted with 25.0 cm3 of potassium hydroxide solution.
The equation for the reaction is:
2KOH + H2SO4 → K2SO4 + 2H2O
Calculate the concentration of the potassium hydroxide solution in mol/dm3 and in g/dm3
Relative atomic masses (Ar): H = 1 O = 16 K = 39.
My specific question is when calculating the Mr of a specific compound do you count the coefficient? Here, do you count the 2 in front of KOH?
Can you please help solve this question step by step and illustrate?

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My specific question is when calculating the Mr of a specific compound do you count the coefficient? Here, do you count the 2 in front of KOH?
Can you please help solve this question step by step and illustrate?

You don't include the 2 when working out the Mr or the KOH, you will need to use it when you have first worked out the number of mol of H2SO4 and then used the 1:2 ratio to work out the number of mol of KOH, then work out its conc. in mol/dm3. You'll use the Mr of the KOH again, to work out the conc. in g/mol.

Don’t include the 2 in front of KOH when calculating the Mr !!

Mr means the molar mass, in other words: it is the mass for one molecule. You must not double it, that is just needed when you have to calculate the amount of a mass for a substance.

This question is about the extraction of metals. Element R is extracted from its oxide by reduction with hydrogen. The equation for the reaction is: 3H2 + RO3 → R + 3H2O
The sum of the relative formula masses (Mr) of the reactants (3H2 + RO3) is 150 Calculate the relative atomic mass (Ar) of R. Relative atomic masses (Ar): H = 1 O = 16 [2 marks]
This is from 2021 paper 1 aqa. The mark scheme includes the 3 in front of the hydrogen when working out the relative atomic mass. Why does it do that?

They have given you the total Mr of all the reactants (as they have specified, 3H2 + RO3) and so you need to know what three times the Mr of H2 (3 x 2 = 6) is so you can subtract it and work out the Mr of RO3 (150 - 6 = 144) and thus the Ar of R (144 - 3 x 16 = 96).
This is a bit of a weird question and I’d be surprised if it (or similar) came up again.