Magnesium nitrate, magnesium hydroxide and magnesium carbonate all decompose when heated. Which statement about these decomposition reactions is correct?
A. Magnesium carbonate decomposes to release carbon dioxide and oxygen
B. Magnesium hydroxide decomposes to release hydrogen and oxygen
C. Magnesium hydroxide decomposes to release water vapour
D. Magnesium nitrate decomposes to release oxygen only

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.)

How many moles is 14.5 cm^3 of platinum? the density of platinum is 21.45 g/cm^3.

Why is retrograde motion an apparent motion