Answer:
0.0008 mole of HCl
Explanation:
From the balanced equation between HCl and NaOH:
1 mole of acid requires 1 mole of base for neutralization.
mole = molarity x volume
mole of NaOH = 0.02 x 0.04 = 0.0008 mole
mole HCl = 0.16 x 0.01 = 0.0016 mole
Since 1 mole of NaOH requires 1 mole of HCl for neutralization, it means that 0.0008 mole of NaOH will require 0.0008 mole of HCl. The remaining mole of HCl must have been neutralized by the antiacid:
0.0016 - 0.0008 = 0.0008 mole.
Therefore, 0.0008 mole of HCl must have been neutralized by the antiacid.