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Question

Mercury (ii) oxide decomposes to form mercury and oxygen gas. What volume of oxygen gas, measured at 150 degree C and 120.3 kPa, is produced by the decomposition of 7.8 grams of mercury(ii)oxide?

Answer 1

Note the DOWN votes on each of your questions.  This is because you are just posting homework problems for tutors to do for you.  You should at least attempt them, and then ask for assistance showing what you've done by yourself.  For example, in this problem you could have written the balanced equation and made an attempt to do the calculations.

Mercury(II) oxide is HgO and decomposition ==> Hg + O2(g) so balanced equation is 2HgO ==> 2Hg + O2(g)

From there, you find moles of HgO in 7.8 g of HgO, and from the stoichiometry of the equation, you determine moles O2 formed.  From there you use PV = nRT to find the VOLUME of O2 produced.