I need help on identifying four elements.

Question

1. a member of the same family as oxygen whose most stable ion contains 54 electrons. (Sulfur?)
2. member of alkali metal family whose most stable ion contains 36 electrons. (Cesium??)
3. noble gas with 18 protons in nucleus (argon?)
4. halogen with 85 protons and 85 electrons (Astatine?)

Thanks

3 and 4 are correct.
For 1.
Look for the oxygen family. Sulfur is a member of that family BUT it has an atomic number of 16 and two extra electrons to fill its outer shell will be only 18. So look down the column and find one that adds two electrons to make 54.
For 2.
The alkali metal family is group I and those elements lose one electron to become the X^+ ion. Cs has an atomic number of 56; therefore, losing 1 electron will leave it with 55 so that isn't the right answer. I think you will get the idea from this discussion. Post your work for #1 and 2 if you want us to check your answers.

1. Tellurium
2. Rubidium

Te and Rb are correct.