12.50 g of a hydrated form of copper(II) sulfate, CuSO4•x H2O (where x is unknown) is gently heated. When all the water has been driven off, the mass of the anhydrous copper(II) sulfate is found to be 7.99 g. What is the mass of the water that was lost as a result of the heating? Convert this mass of water to moles of water. Convert the mass of the anhydrous CuSO4 to moles. Divide the answer to b by the answer to c. This is the value of x in the formula of the hydrate. Write the formula of hydrated copper(II) sulfate.

1) Total mass of the compound: 
  = CuSO₄ * 5H₂O
 = 63.5 + 32 + 16*4 + 5[1 * 2 + 16]
 = 95.5 + 64 + 90
 = 249.5 amu

b) Mass of water in compound = 5H2O = 5 [1 * 2 + 16] = 90 amu

c) Percentage of water = 90/249.5 * 100 = 36.07%

29) We know, Equation of Charles law:
 V1T1 = V2T2
Here, V1 = 725 mL
T1 = -35 + 273 = 238 K
T2 = 25 + 273 = 298 K

Substitute their values, 
725*238 = v2*298
v2 = 172550 / 298
v2 = 579.02 mL

30.) At higher altitudes, Atmospheric pressure is very lower, so foods take longer to cook. In order to save some time due to such a low pressure, there are some instructions for that.

Hope this helps!