Answer: Th enthalpy of combustion for the given reaction is 594.244 kJ/mol
Explanation: Enthalpy of combustion is defined as the decomposition of a substance in the presence of oxygen gas.
W are given a chemical reaction:



To calculate the enthalpy change, we use the formula:

This is the amount of energy released when 0.1326 grams of sample was burned.
So, energy released when 1 gram of sample was burned is = 
Energy 1 mole of magnesium is being combusted, so to calculate the energy released when 1 mole of magnesium ( that is 24 g/mol of magnesium) is being combusted will be:

Answer:
D. If the acid was separated from the vinegar, chicken bones wouldn't become bendy in the remaining vinegar.
Explanation:
The hypothesis states that the bone becomes bendy because of the acid in the vinegar, so therefore, if the acid is removed from the vinegar it won't become bendy.
First step: convert 22.4% into fraction
that is 22.4/100 which is equivalent to 0.224
The mass of Cucl2 contained in 75.85 of 22.4% by mass of solution of CUcl2 in water is therefore,
0.224 x75.85=16.99g
alternatively
75.85 --->100%
? 22.4%
by cross multiplication =(22.4 x 75.85)/100 =16.99g