The compound is calcium carbonate
now you can solve ur 4 question like this => The masses of two liquids are equal, let it be m.
Let the relative densities of water and liquid be ρ1and ρ2 respectively.
The volume of the two be V1 and V2, of water and liquid respectively.
The volume of the mixture would be, V = V1 + V2 (1)
also, volume = mass/density
2m/ρ (V) = m/ρ1 (V1) + m/ρ2 (V2)
here ρ1 = 1, ρ2 = 2 and ρ is the relative density of the mixture.
2/ρ = 1/ρ1 + 1/ρ2
by substituting the values, we
ρ/2 = 2/3
or, the relative density of the combined liquid will be, ρ= 4/3
the correct option would be (b)