Answer:
Mass of 1 mole of copper is 63.83 g.
0.03916 moles of copper atoms have a mass equal to the 2.5 grams of copper penny.
Explanation:
Mass of 1 copper atom,m = 

Mass of 1 mole of copper :
= 
Mass of 1 mole of copper = 63.83 g
Mass of copper penny = 2.5 g
Atomic mass of copper = 63.83 g/mol
Moles of copper in 2.5 g of copper penny:

0.03916 moles of copper atoms have a mass equal to the 2.5 grams of copper penny.
Complete Question
The complete question is shown on the first uploaded image
Answer:
The concentration equilibrium constant is 
Explanation:
The chemical equation for this decomposition of ammonia is
↔ 
The initial concentration of ammonia is mathematically represented a
![[NH_3] = \frac{n_1}{V_1} = \frac{29}{75}](https://tex.z-dn.net/?f=%5BNH_3%5D%20%3D%20%20%5Cfrac%7Bn_1%7D%7BV_1%7D%20%20%3D%20%5Cfrac%7B29%7D%7B75%7D)
![[NH_3] = 0.387 \ M](https://tex.z-dn.net/?f=%5BNH_3%5D%20%3D%200.387%20%20%5C%20%20M)
The initial concentration of nitrogen gas is mathematically represented a
![[N_2] = \frac{n_2}{V_2}](https://tex.z-dn.net/?f=%5BN_2%5D%20%3D%20%20%5Cfrac%7Bn_2%7D%7BV_2%7D)
![[N_2] = 0.173 \ M](https://tex.z-dn.net/?f=%5BN_2%5D%20%3D%20%200.173%20%20%5C%20%20M)
So looking at the equation
Initially (Before reaction)


During reaction(this is gotten from the reaction equation )
(this implies that it losses two moles of concentration )
(this implies that it gains 1 moles)
(this implies that it gains 3 moles)
Note : x denotes concentration
At equilibrium


Now since
![[NH_3] = 0.387 \ M](https://tex.z-dn.net/?f=%5BNH_3%5D%20%3D%200.387%20%20%5C%20%20M)
Now the equilibrium constant is
![K_c = \frac{[N_2][H_2]^3}{[NH_3]^2}](https://tex.z-dn.net/?f=K_c%20%20%3D%20%20%5Cfrac%7B%5BN_2%5D%5BH_2%5D%5E3%7D%7B%5BNH_3%5D%5E2%7D)
substituting values


Answer:
3Mg(s) +2P(s) -------> Mg3P2(s) + energy
Keq= [Mg3P2]/[Mg]^3 [P]^2
Explanation:
The equation for the formation of magnesium phosphide from its elements is;
3Mg(s) +2P(s) -------> Mg3P2(s) + energy
Hence we can see that three moles of magnesium atoms combines with two moles of phosphorus atoms to yield one mole of magnesium phosphide. The equation written above is the balanced chemical reaction equation for the formation of the magnesium phosphide.
The equilibrium expression for the reaction K(eq) will be given by;
Keq= [Mg3P2]/[Mg]^3 [P]^2