Answer:

Explanation:
The contact between the sheet of gold and the sheet of iron allows a heat transfer until thermal equilibrium is done, which means that both sheets have the same temperature:






The final temperature is:

Answer:
w = -531 kJ
1. Work was done by the system.
Explanation:
Step 1: Given data
- Heat gained by the system (q): 687 kJ (By convention, when the system absorbs heat, q > 0).
- Change in the internal energy of the system (ΔU°): 156 kJ
Step 2: Calculate the work done (w)
We will use the following expression.
ΔU° = q + w
w = ΔU° - q
w = 156 kJ - 687 kJ
w = -531 kJ
By convention, when w < 0, work is done by the system on the surroundings.
Im not sure but it could be 4 (H)
Atomic mass Hg = 200.59 u.m.a
200.59 g --------------- 6.02x10²³ atoms
( mass Hg ) ----------- 1.20 x10²² atoms
mass Hg = ( 1.20x10²² ) x 200.59 / 6.02x10²³
mass Hg = 2.407x10²⁴ / 6.02x10²³
= 3.998 g of Hg
hope this helps!