E = m c^2
E is energy in joule, m is mass in Kg and c ....speed of light (as you mention)
Substituting your values in the equation
E = ( 5.63 x 10-7kg ) (3*10?^8) ^2 = 5.067 *10 ^10 J
2H2O=2H2+O2
37.4g H2O(1 mol/18.02)=2.07547 mol H2O
PV=nRT
(1.30)(V)=(2.07547)(.0821)(297)
Vwater=38.92898L
38.92898L (1 mol O2/2 mol H2O)=19.46449L O2 gas
The number of significant figures within a number are the amount digits that are required to specify a number to a certain degree of accuracy. In the number, 0.0645 g, the 6 is the most significant figure and 4 is the second most significant figure. Therefore, rounding to two significant figures yields 0.064g.
In order to apply the principle of conservation of mass to this reaction, we must prove that the mass on the left hand side is equivalent to the mass on the right hand side. In order to do this, we must first acquire the atomic masses of each substance involved. These are:
Fe - 56
O - 16
Now, we substitute these values into the equation:
4(56) + 3(2*16) = 2(56 * 2 + 16 * 3)
224 + 96 = 320
320 = 320
As we can see, the principle of conservation of mass holds true.
Answer: 1. 3.23 m
2. 32.4
3. B adding solvent and C removing solute
Explanation:
1. Molality of a solution is defined as the number of moles of solute dissolved per kg of the solvent
where,
n = moles of solute
= weight of solvent
Now put all the given values in the formula of molality, we get
2. Molarity of a solution is defined as the number of moles of solute dissolved per liter of the solution.
where,
n = moles of solute
= volume of solution in L
Therefore, the moles of 
is 32.4
3. Molarity can be decreased by decreasing the moles of solute and by increasing the volume of solution.
Thus adding solvent and removing solute will decrease the molarity.
