One way of producing drinking water from seawater is by reverse osmosis. Reverse osmosis is a type of filtration. Seawater is pushed through a semi-permeable membrane. Pressure is applied to the seawater. Semi-permeable
means salt is trapped on one side of the membrane, but water can pass through.
The trapped salts form a ‘seawater concentrate’ on one side of the membrane.
Where do the trapped salts go?

[a] ocean [b]Water distribution system
[c]Storage tank [d]delivery pipeline
QUESTION 3:
Based on the above picture what will determine whether a particle is able to pass
through the membrane?
[a] particle size [b] particle mass
[c] number of particles [d] charge on the particle

the trapped salts go to seawater concentrate

answer: - first one is the correct answer. .

explanations: - potassium sulfide is and cobalt(ii) chloride is .

charge on k is +1, charge on s is -2, charge on co is +2 and charge on cl is -1.

in a double replacement reaction the ion exchange takes place. in general the reaction looks like:

if one of the product is insoluble as per solubility rules then a precipitate of it is formed.

when we mix the aqueous solutions of potassium sulfide and cobalt(ii) chloride then chloride ion goes with potassium ion and sulfide ion goes with cobalt ion and the balanced equation is written as:

k and cl has equal charges, similarly co and s has equal charges and hence no subscripts are used for the product side.

as per the solubility rules, cos is insoluble and so it's precipitate is formed.

looking at the given choices, first choice is correct.