Iodine would be your answer!!!
X4O10
Let molar mass of X be y
molar mass = 4y + 10 x 16 = 4y+160
so, moles = 85.2 / (4y+160)
Moles of oxygen = 10 x [85.2 / (4y+160) ]
Mass of oxygen = 16 x 10 x [85.2 / (4y+160) ]
which is 48.0
so, 48 = 16 x 10 x [85.2 / (4y+160) ]
Solve the equation to get y.
y = 31
We subtract the enthalpies of the reactants from that of the products:

Since this is < 0, this is an exothermic reaction.
Answer:
199920J
Explanation:
Given parameters:
Mass of steam = 85g
Unknown:
Heat released when the liquid is condensed = ?
Solution:
The heat released by the substance is given as;
H = mL
H is the heat released
m is the mass
L is the latent heat of steam = 2352J/g
Heat released = 85 x 2352 = 199920J