Answer: 207.24
Explanation: Atomic mass = no of protons + no of neutrons
1) 82 protons, 122 neutrons , mass number= 82+122 = 204
2) 82 protons, 125 neutrons, mass number= 82+125 = 207
3) 82 protons, 124 neutrons, mass number= 82+124 = 206
4) 82 protons, 126 neutrons, mass number= 82+126 = 208
Average atomic mass of an element = 
Average atomic mass of given element = 
The approximate atomic mass of lead is 207.24.
Answer:
If the half-life of 14C is 5730 years, when this period of time has passed it will have been halved, it is called the exponential decay law of radioactive isotopes.
Salted butter does not need to be stored in the fridge since the risk of bacterial growth is so low. ... However, it will stay fresh longer if it is kept in the refrigerator. Refrigeration slows down the process of oxidation, which will eventually cause butter to go rancid.
I hope this helps!
Answer:
-162,5 kJ/mol
Explanation:
Cl(g) + 2O2(g) --> ClO(g) + O3(g) ΔH = 122.8 kJ/mol (as we used the reaction in the opposite direction, it will turn the enthalpy from exothermic to endothermic)
2O3(g) --> 3O2(g) ΔH = -285.3 kJ/mol
Cl(g) + O2(g) --> ClO(g) + O3(g) ΔH = 122.8 kJ
+ 2O3 (g) --> 3O2(g) ΔH = - 285.3 kJ
O3(g) + Cl(g) --> ClO(g) + 2O2(g) ΔH = 122.8 + (-285.3) = -162,5 kJ
