Data

Volume of NaOH = 100cm³
Molanty of NaOH = 1M
Volume of HCl = 100 cm³
Molarity of HCl = 0.1M

Asked
a/ ions in excess
b/ concentration of excess

Solution
For NaOH,
1 mole Ξ 100 cm³
?? Ξ 100cm³

(1 mole × 100 cm³) /1000cm³
= 0.1 mole of NaOH for HCl

0.1 mole Ξ 1000cm³
?? Ξ 100cm

(0.1 M × 100 cm³) / 1000
= 0.01 mole of HCl

a) The ions of excess are sodium hydroxide solution (NaOH)
b) The concentration of excess solution (NaOH) was found to be 0.01M