1.6 m h2so4 is carelessly substituted for 6 m hcl. will more or fewer drops of 6 m h2so4 be required for the litmus to change color?

Answer is: fewer drops of 6 M sulfuric acid, because concentration of H⁺ is greater than in hydrochloric acid with same concentration.

Chemical dissociation of hydrochloric acid in water: 
HCl(aq) → H⁺(aq) + Cl⁻(aq).
Chemical dissociation of sulfuric acid in water: 
H₂SO₄(aq) → 2H⁺(aq) + SO₄²⁻(aq).
From chemical reaction: c(HCl) = c(H⁺) = 6 M.
c(H⁺) = 2c(H₂SO₄) = 2 · 6 M = 12 M; concentration of hydrogen cations.

The activity series is shown in the attached picture. if the element is below the other, then you can displace the other. following the activity series as a guide, the reactions are as follows: nickel and aluminum chloride3 ni + 2 alcl₃  → 3 nicl₂ + 2 albarium and copper bromideba + cubr  →  no reaction because cu is less oxidizable than bapotassium nitrate and aluminum3 kno₃ + al  → al(no₃)₃ + 3 ksodium phosphate and zincnaso₄ + zn  → znso₄ + na