Answer:
Balance molecular equation:
K2CO3(aq) + Sr(NO3)2(aq) → SrCO3(s) + 2KNO3(aq)
Net ionic equation:
CO3∧-2(aq) + Sr∧+2(aq) → SrCO3(s)
Explanation:
Potassium carbonate = K2CO3
Strontium nitrate = Sr(NO3)2
Chemical equation:
K2CO3 + Sr(NO3)2 → SrCO3 + KNO3
Balance chemical equation with physical states:
K2CO3(aq) + Sr(NO3)2(aq) → SrCO3(s) + 2KNO3(aq)
Ionic equation:
2K+(aq) + CO3∧-2(aq) + Sr∧+2(aq) + 2NO∧-3(aq) → SrCO3(s) + 2K+(aq) + 2NO∧-3(aq)
Net ionic equation:
CO3∧-2(aq) + Sr∧+2(aq) → SrCO3(s)
2K+ and 2NO∧-3 ions are spectator ions that's way these are not written in net ionic equation.
Spectator ions:
These are the ions that are present same on both side of chemical reaction and does not effect the equilibrium.
Answer:
20.468 kilo Joules is the enthalpy change when one mole of sodium nitrate dissolves.
Explanation:
Heat lost by solution ad calorimeter = Q
Heat capacity of solution ad calorimeter = C = 1071 J/°C
Change in temperature = ΔT = 21.56°C - 25.00°C = -3.44°C


Heat gained by sodium nitrate = -Q = -(-3,684.24 J)=3,684.24 J
Moles of sodium nitrate = 
When 0.18 mole of sodium nitrate was dissolved in water 3,684.24 joulesof heat was absorbed by it.
Then heat absorbed by 1 mole of sodium nitrate :

1 J = 0.001 kJ
20.468 kilo Joules is the enthalpy change when one mole of sodium nitrate dissolves.
Answer:
C9H13N
Explanation:
Since there is no common factor besides 1, the formula is already the empirical formula for this compound.
Answer:
He2 molecule contains 4 electrons. Each atom gives 2 electrons in 1s orbitals. This way 2 (1s) orbitals combine to give 2 molecular orbitals viz. ... This indicates that there is no bond formation between 2 HE atoms and hence the He2 molecule does not exist.
Explanation: