Isotope A contains 56 protons and 80 neutrons. Isotope B contains 55 protons and 81 neutrons. Isotope C contains 57 protons and 80 neutrons. Isotope D contains 56 protons and 74 neutrons.
Which are isotopes of the same element?
Isotopes A and D only
Isotopes B and C only
Isotopes A and C only
Isotopes A and B only

- decrease the number of plants and animals living in the water.

plasma - state of matter made up of electrically charged particles

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.