It would be elliptical according to him.....
The formula of the compound is XY. This means that the relation between the moles is 1: 1. One mole of X per one mole of Y.
From the information about the element X you can determine the number of moles of X (which is the same that the number of moles of Y).
# of moles of X = weigth of X / atomic mass of X = 17.15 g / 22.9 g/mol = 0.74598
Now the atomic mass of Y = weight of Y / # of moles of Y = 14.17 g / 0.74598 mol = 19 amu
The H3O+ in a 0.050M solution of Ba(OH)2 is calculated as below
write the equation for the dissociation of Ba(OH)2
Ba(OH)2 = Ba^2+ +2OH^-
calculate the OH- concentration
by use of mole ratio between Ba(OH)2 to OH^- which is 1:2 the concentration of OH = 0.050 x2 = 0.1 M
by use of the formula ( H3O+)(OH-) = 1 x10 ^-14
by making H3O+ the subject of the formula
H3O+ = 1 x10^-14/ OH-
substitute for OH-
H3O+ = (1 x10^-14 )/0.1
= 1 x10^-3 M
<u>Answer: </u>The correct answer is Option A.
<u>Explanation:</u>
Fluorine is the 9th element in the periodic table which belongs to group 17 and period 2. It is a non-metal because it requires an electron to gain its stable electronic configuration.
The electronic configuration of this elements is: 
This element requires 1 electron to attain stable configuration. It is an insulator and is not lustrous.
This element easily gains an electron and hence, is considered as a highly reactive non-metal.
Hence, the correct answer is Option A.
The classification of it being a metal, nonmetal, or metalliod will be useful in the process of elimination to determine what it is. Then for the second test, meauring the atomin radius will narrow it down quicker to the mystery elemet's name.
Since you determined what part of the periodic table it's on, then when measuring the atomic radius, you should be able to pinpoint what the element is more surely.
