More Chemistry Questions !

If anyone could answer any of these questions and explain how you work them out it would be much appreciated :confused:

1. When 3.6g of butanal (relative formula mass = 72) was burned, 134 KJ of energy of energy was released.

From this result, what is the enthalpy of combustion, in KJ mol -1.

a) -6.7
b) +6.7
c) -2680
d) +2680

2. 5g of copper is added to excess silver nitrate solution. The equation for the reaction that takes place is;

Cu(s) + 2AgNO3(aq) ------> 2Ag(s) + Cu(NO3)2(aq)

After some time, the solid present is filtrated off from the solution, washed with water, dried and weighed.

The final mass of the solid will be
a) less than 5g
b) 5g
c) 10g
d) more than 10g

3. Two identical samples of zinc were added to an excess of two solutions of sulphuric acid, concentrations 2 mol -1 and 1 mol -1 respectively.

Which of the following would have been the same for the two samples?
a) The total mass lost
b) The total time for the reaction
c) The initial reaction rate
d) The average rate of evolution of gas

4. It is now known that protons and neutrons are made up of small particles called quarks.
Each proton and each neutron contains 3 quarks.
What is the approximate number of quarks in 1g of carbon-12?
a) 6 x 10 to the 23
b) 9 x 10 to the 23
c) 1.8 x 10 to the 24
d) 2.16 x 10 to the 25