A sample of magnesium metal was placed in a solution of hydrochloric acid producing magnesium chloride and hydrogen gas. The hydrogen was collected by water displacement at 25.0oC and found to have a total pressure of 1.10atm and a volume of 2.00L. If the vapor pressure of water at 25.0oC is 0.03126 atm, how many grams of magnesium were used in the reaction?

That is a lot of moles that you have

Reaction involved in present system is :   c12h22o11 + h2o → 2 c6h12o6the reaction system is obeying following rate law:   rate = k[c12h22o11]thus, it is a first order reaction.now, for 1st order reactionrate constant (k) =  given: initial conc. = 3.0 g, final conc. = 2.7 g, t = 2.5 h∴rate constant (k) =  ∴ k = 0.04215 h-1now, for 1st order reaction, half life = 0.693/k = 0.693/0.04215 = 16.4 hthus correct answer is option b

Chromosomes can be used more than once atoms are all different