1. What is the final temperature of a solution in which 3.88g of NH4NO3 is dissolved in 60.0mL of water? The initial temperature of the mixture is 23.0C, the specific heat of the solution is the same as water, and the reaction absorbed 1.23kJ of heat.

2. Give the oxidation numbers of all the elements and ions in the molecule below. KH2PO3

3. A 6.53g sample of a mixture of magnesium carbonate and calcium carbonate is treated with excess hydrochloric acid. The resulting reaction produces 1.72L of carbon dioxide gas at 28^oC and 743 torrs.
(a) Write a balanced chemical equation for the reactions that occur between HCl and each of the components of the mixture.
(b) Calculate the total moles of carbon dioxide formed.
(c) Assuming that both reactions are complete, calculate the percent by mass of magnesium carbonate in the mixture.

Here are the answers that i got (without the work, but if they're wrong, i'd like to see where i went wrong ofcourse).

1A. Actually, couldn't figure this one out :(
2A. K=+1, H=+2, P=-3, O=-6
3Aa. MgCO + CaCO + HCl ==> CO2 + McCl2 + CaCl2 + CH4
3Ab. 0.00155 mol of CO2
3Ac. 43.45% MgCO

Thanks in advance for your help.