Answer:
It is B
Explanation:
I was able to find my school notes and double-check. I hope you have a nice day!
Answer:
Rb<K<Ga<As<Se<S
Explanation:
We must remember that first ionization energy decreases down the group and increases across the period.
First ionization energy decreases down the group because of the addition of more shells which increases the distance between the nucleus and the outermost electron. Hence, Rb has a lower ionization energy that K.
Across the period, increase in the size of the nuclear charge causes the pull of the nucleus on the outermost electrons to increase thereby increasing the ionization energy. Hence ionization energy increases across the period. For this reason, the ionization energy of Ga<As<Se as shown.
Answer: 
Explanation: Because barium is in Group 2, it forms ions with a charge of +2. Fluorine, in Group 17, form ions with a charge of -1. Cross the charges to get the subscripts (Since Ba has a charge of +2, F has a subscript of 2. Because F has a charge of -1, Ba needs a subscript of 1). Therefore, a formula unit of the compound is .
The atomic number is the numbers of protons
Its a echo being used in that picture so if i was ypu you should classify my answer
