the concentration of nickel in nigeria coin was delivered with visible spectrophotometer and the following result in percentage was obtained: 3.65,3.59,3.87,4.06,4.11,7.5,3.95,1.48,3.60,3.76 and 3.99.If the true percentage concentration of nickel in coil was determined by atomic absorption and inductively copied plasma,atomic emission spectrophotometer was 3.92,used the above data to determine the absolute error

Assuming that zinc displaces the hydrogen as the cation in HCl, and assumes its natural charge of 2+, it requires two Cl- to make the zinc chloride compound. Therefore, we know there need to be two HCl atoms in the equation, and that the resulting compound ZnCl2 requires us to account for two lost hydrogen atoms, which will come out as natural diatomic gas:
Zn(s) + 2HCl(aq) --> ZnCl2(aq) + H2(g)