Cobalt-59 and Cobalt-60 differ in that they have different mass number which means they have different number of neutrons. Isotopes are atoms of the same element with similar atomic number but different mass number. Cobalt-60, has a number of uses, which includes, being used to irradiate food sources as a method of preserving food, used in industrial radiography to detect structural flaws in metal parts among other uses.
Answer: 2.8 moles of copper (Il) sulfide 
will be produced from 2.8 moles of sulphur.
Explanation:
The balanced chemical reaction is:
According to stoichiometry :
1 mole of 
produce = 1 mole of copper (Il) sulfide
Thus 2.8 moles of will produce=
of copper (Il) sulfide
Thus 2.8 moles of copper (Il) sulfide will be produced from 2.8 moles of sulphur.
Answer:
The 2s orbital is at a higher energy level.
Explanation:
1s and 2s are the sub-orbitals that are located in an atom. They are nearest to the nucleus and are found on the s sub-orbital. The difference between 1s and 2s is the difference in their level of energy. 1s has low energy as compared to 2s. 1s orbital has the lowest energy because it is located closed to the nucleus. 2s orbital has higher energy than 1s because it's orbit is larger than 1s.
The answer is 4.69 x 10⁻¹⁹ I hope this helped!
