Quantum Mechanical model (as per my knowledge)
Answer:
Explanation:
The Ce metal has electronic configuration as follows
[Xe] 4f¹5d¹6s²
After losing 4 electrons , it gains noble gas configuration ,. So Ce ⁺⁴ is stable.
Eu has electronic configuration as follows
[ Xe ] 4 f ⁷6s²
[ Xe ] 4 f ⁷
Its outermost orbit contains 2 electrons so Eu²⁺ is stable. Its +3 oxidation state is also stable.
Ce⁺²
From Q = mcΔT, we can rearrange the equation to solve for mass, m = Q/cΔT. The specific heat capacity, c, of solid gold is 0.129 J/g °C. I'm assuming that the energy is given in joules, as it's not specified in the question as written.
m = Q/cΔT = (35.73 J)/(0.129 J/g °C)(40.85 °C - 0.85°C)
m = 6.92 g of gold was present
There are 5.43 x 10²³ present in 187 grams of XeF₄
<h3>Further explanation </h3>
The mole is the number of particles(molecules, atoms, ions) contained in a substance
1 mol = 6.02.10²³ particles
Can be formulated
N=n x No
N = number of particles
n = mol
No = Avogadro's = 6.02.10²³
Moles can also be determined from the amount of substance mass and its molar mass

mass of XeF₄ = 187 g
mol XeF₄ (MW=207,2836 g/mol) :

Number of molecules :
