The heat is involved in the production of 5.0 mol of MgO is 180 Kj
calculation
2 Mg (s) +O2 → 2 MgO
From the equation above two moles of MgO is used therefore
72.3 is for 2 moles
that is 72.3 kj = 2moles
? = 5 moles
by cross multiplication
= 72.3 kj × 5/2 = 180 Kj
Answer:
When a atom is unstable (It wants to gain or lose a valence electron)
Answer:
The Letter I
Explanation:
There are two flat horizontal lines. Those are phase changes. I is the solid state before the first phase change where the substance goes from a solid to a liquid.
So the answer is I
Atomic number=number of protons (and electrons, but that doesn't matter in this answer)
Atomic mass=number of protons+number of neutrons
Atomic mass=atomic number+number of neutrons
Atomic mass-atomic number=number of neutrons
88-38=number of neutrons
number of neutrons=50
The mass of impure 
is 20.7167 g. The decomposition reaction is as follows:
Here, 1 mole of gives 1 mole of MgO.
Molar mass of and MgO is 84.31 g/mol and 40.3044 g/mol respectively.
Converting number of moles in terms of mass,
Here, M is molar mass.
Since, 
Thus, 
On putting the values,
Rearranging,
Or,
...... (1)
Let the mass of impurity be 
and mass of impure is 20.7167 g thus,
...... (2)
Also, mass of impure MgO is 16.8817 g thus,
...... (3)
On comparing equations (2) and (3),
Putting the value of 
in equation (1),
Or,
Or,
Or,
Or,
Thus, magnesium carbonate present in the original sample is 7.35 g.
