A C and D are all correct, Helium and Hydrogen only have a 1s orbital, and helium has 2 protons, while hydrogen has 1, and finally Hydrogen has no neutrons while helium has 2. Helium does not however have 8 valence electrons as the 1s orbital can only hold 2, meaning B is the “correct” (false) answer.
An x would represent the gained electrons
A . Would represent the valence electrons
You would just draw [ ] around the diagram
And the charge should be placed outside the brackets
<span>A chemist adds 155.0ml of a 4.10 X 10^-5 mmol/L of a zinc oxalate (ZnC2O4)solution to a reaction flask. Calculate the mass in micrograms of zinc oxalate the chemist has added to the flask.
1mmol = 10^-3 mol
Therefore 4.10*10^-5mmol = 4.10*10^-8mol
molar mass ZnC2O4 = 65.39+(2*12.011)+(4*15.99) = 153.372g/mol
You have 4.10*10^-8 mol/litre =153.372 * 4.10*10^-8 = 6.29*10^-6 grams / litre (* see below)
But you have 155ml. Mass of ZnC2O4 = 155/1000*6.29*10^-6 g
Mass is = 9.75*10^-7 grams
1µg = 10^-6 g
You then have 9.75*10^-7/10^-6 = 0.975µg ZnC2O4
(*see below) at this point you could have said:
1µg = 10^-6 g therefore you have a solution of 6.29µg per litre,
155ml = 6.29*155/1000 = 0.975µg ZnC2O4</span>
To know the density you also need to know the volume of the rock.
(a)The change in Gibbs free energy for the reaction has been 2.6 kJ/mol.
(b) The change in Gibbs free energy for the reaction has been -49.3 kJ/mol.
(c) The change in Gibbs free energy for the reaction has been 91.38 kJ/mol.
