Find the ΔHr0 for the reaction:
Na2CO3(s) +2HNO3(aq) → 2NaNO3(s) +CO2(g) +H2O(l)

ΔHr0=+125.7kJ

ΔHr0=-67.2kJ

ΔHr0=-45.3kJ

ΔHr0=-140.0kJ

ΔHr0=+105.8kJ

1) how many electrons are in each energy level of the following elements? a. he b. na c. na d. ne 2) how many valence electrons are percent in the following atoms? a. s b. mg c. be d. cl 3) which of the following elements are stable as atoms? a. he b. o c. cl d. ar if you are able to provide the work as to how you got the answers that would be greatly appreciated. : )

Which metal exist in liquid state and can be cut with knife ?

How is the atomic number of a nucleus changed by alpha decay