We first have to find Q calorimeter
Q calorimeter = C (delta T)
C= heat capacity in J/oC, not small c ( specific heat capacity)
delta T= change in T (oC) = final T - initial T
Q calorimeter = 10.4 J/oC (30 oC - 25 oC)
Q calorimeter = 52 J
Remember,
Q calorimeter = - Q surrounding
The (-) negative sign stands for heat being released.
So ,
Q surrounding = - 52 J
In other words, the iron releases 52 J .
The calorimeter absorbs the entire 52 J and heat rose from 25 - 30 oC.
Answer: 52 J
When an atom becomes an anion it loses ions, so its becoming smaller
That is because Alchemy is not based on real research and facts, but rather on magic and occultism. Sure, many things in it have been used as basics for some chemistry, but most is false and incorrect.
Here you are looking on the Free Body diagram of a net force of 0N in both the x and y-directions. the only ones that has that condition met is A and C.