The number of moles of MgO produced when 0.200 mol of O2 reacts completely is

What is the main reason why some developing countries fear the increase the free trade policies around the world?

Modern pennies are composed of zinc coated with copper. a student determines the mass of a penny to be 2.482 g and then makes several scratches in the copper coaling (to expose the underlying zinc). the student puts the scratched penny in hydrochloric acid, where the following reaction occurs between the zinc and the hcl (the copper remains undissolved): zn(s) + 2 hcl(aq) → h2(g) + zncl(aq)the student collects the hydrogen produced over water at 25 °c. the collected gas occupies a volume of 0.899 l at a total pressure of 79 j mmhg. calculate the percent zinc (by mass) in the penny. (assume that all the zn in the penny dissolves.)

Calculate the frequency of a wave in a spring toy. the wave has a speed of 1.1 meters per second and a wavelength of 0.1 meters. *