The acid base reaction equation is as follows;
HCl + NaOH ---> NaCl + H₂O
stoichiometry of HCl to NaOH is 1:1
NaOH is a strong base and HCl is a strong acid they completely dissociate into its ions
number of HCl moles - 0.16 mol/L x 0.200 L = 0.032 mol
number of NaOH moles - 0.091 mol/L x 0.300 L = 0.0273 mol
Limiting reactant is NaOH therefore number of HCl moles reacted - 0.0273 mol
the excess amount of HCl moles are - 0.032 - 0.0273 = 0.0047 mol
since HCl is a strong acid
total volume - 200 mL + 300 mL = 500 mL
[HCl ] = [H⁺]
therefore [H⁺] = 0.0047 mol / 0.500 mL
[H⁺] = 0.0094 mol/L
hydroxide ion concentration - 0.0094 M
The link below is a picture of the "Waning gibbus" phase, really hope that it helps you out :D
There is 7 sig figs in that number
Silicon and Germanium. You can conclude it from its position in the periodic table. Silicon and Germanium are in the same group of the Carbon. That implies that all three have the same number of electrons in the outer orbital, which is responsible for the bonds.