Pressure does not affect the voltage produced in a voltaic cell.
I think the answer is (1) Co. Because the element of Cobalt also has 2 electrons at the outer layer which is the same as Calcium. And the outer layer is an important factor which can affect the property of an element.
The molarity of HBr solution is 0.239 M
calculation
write the equation for reaction
that is LiOH +HBr → LiBr +H20
find the moles of LiOH used
moles =molarity x volume
=0.205 x 29.15 = 5.976 moles
by use of mole ratio between LiOH :HBr which is 1:1 the moles of HBr is therefore= 5.976 moles
Molarity of HCL= moles /volume
= 5.976/25 = 0.239 M
According to boiling point elevation equation:
Δ T = i Kb m
when ΔT (change in boiling point) = 7.10 C°
and i (van't Hoff factor)= 1
and Kb = 0.520
so, by substitution:
7.10 = 1*0.520 *m
m = 7.1 / 0.52 = 13.65 m
