D) Radioactive contamination
Earth is so hot inside that magma erupts and flies out. LOL hope this helps.
Problem One
You will use both m * c * deltaT and H = m * heat of fusion.
Givens
m = 12.4 grams
c = 0.1291
t1 = 26oC
t2 = 1204
heat of fusion (H_f) = 63.5 J/grams.
Equation
H = m * c * deltaT + m * H_f
Solution
H = 12.4 * 0.1291 * (1063 - 26) + 12.4 * 63.5
H = 1660.1 + 787.4
H = 2447.5 or 2447.47 is the exact answer. I have to leave the rounding to you. I have no idea where to round it although I suspect 2450 would be right for 3 sig digs.
Problem Two
Formula and Givens
t1 = 14.5
t2 = 50.0
E = 5680
c = 4.186
m = ??
E = m c * deltaT
Solution
5680 = m * 4.186 * (50 - 14.5)
5680 = m * 4.186 * (35.5)
5680 = m * 148.603 * m
m = 5680 / 148.603
m = 38.22 grams That isn't very much. Be very sure you are working in joules. You'd leave that many grams in the kettle after drying it thoroughly.
m = 38.2 to 3 sig digs.
Water decomposes when electrolyzed to produce hydrogen and oxygen gas. If 2.5 grams of water were decomposed 1.04 grams of oxygen will be formed.
BCA table:
2
O ⇒
+ 
B 0.13 0 + 0
C -0.13 0.065 + 0.065
A 0 0.065
Explanation:
Balanced equation for water decomposition into hydrogen and oxygen gases
2
O ⇒
+ 
B 0.13 0 + 0
C -0.13 0.065 + 0.065
A 0 0.065
Number of moles of water = 
mass = 2.5 grams
atomic mass= 18 grams
number of moles can be known by putting the values in the formula,
n = 
= 0.13 moles
2 moles of water gives one mole of oxygen on decomposition
so, 0.13 moles of water will give x moles of oxygen on decompsition
= 
x = 0.065 moles of oxygen will be formed.
moles to gram will be calculated as
mass =number of moles x atomic mass
= 0.065 x 16
= 1.04 grams of oxygen.