Chemistry

True.
Molar mass of Mg < Molar mass of Zn
Since dilute H2SO4 used is excess,
No. of moles of Mg reacted with H2SO4 > No. of moles of moles of Zn reacted with H2SO4 (with equal mass of Mg and Zn)
Therefore, amount of H2 gas produced by Mg > amount of H2 produced by Zn.

2012-01-14 23:57:13 補充：
Simply speaking, you can let the mass of Mg and Zn be 1g, then by formula of no. of moles = mass/molar mass, and calculate whether Mg or Zn have greater no. of moles available to react with excess H2SO4 to form H2, if you don't understand what I'm doing in the answer.