Answer:
h = h₀/2, the liquid column rises half the height
Explanation:
Pressure is defined as force per area,
P = F / A
in a barometer the force is the weights of the liquid column
F = W = mg
P = m g/A
if we use the definition of density
ρ =
= ρ h
we substitute
P = ρ g h
Let's use the index o for the mercury
P₀ = ρ₀ g h₀
when we change the liquid for another with
ρ = 2ρ₀
the pressure expression is
P = 2ρ₀ g h
in the problem they indicate that the pressure is equal to the initial P = P₀
we substitute
ρ₀ g h₀ = 2ρ₀ g h
h₀ = 2h
h = h₀/2
the liquid column rises half the height