A sample of drinking water is analyzed colorimetrically for ammonia nitrogen concentration. If the sample colour when viewed through a depth of 5.5 cm corresponds in intensity to a 1 mg/L standard sample when viewed through a depth of 40 cm, what is the concentration of ammonia nitrogen in the sample? ​

d : a person who learns about the world by observing it. no that is not a smiley face

explanation:

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.