That is not the correct answer. Since we have diluted the ACID to 10% the number of moles in it is just 1/10 of the original concentration

You are correct. When the acid is diluted to 10% concentration, the number of moles of the acid in the solution is indeed reduced to 1/10 of the original concentration.<br /><br />To calculate the number of moles of the acid in the diluted solution, we can use the formula:<br /><br />Number of moles = Concentration (in mol/L) x Volume (in L)<br /><br />Given that the diluted concentration is 10% (or 0.1 mol/L) and the volume of the diluted solution is 0.5 L, we can calculate the number of moles as follows:<br /><br />Number of moles = 0.1 mol/L x 0.5 L = 0.05 mol<br /><br />Therefore, the number of moles of the acid in the diluted solution is 0.05 mol.