Drag and drop each chemical equation into the correct box to match its word equation.

note: there is an extra chemical equation that does not match with any of the word equations.

The reaction corresponding to 1st option is Fe + S - > FeS

Reaction corresponding to 2nd option is 2Hg + O₂ - > 2HgO

Reaction corresponding to 3rd option is Ca + 2 H₂O - Ca(OH)₂ + H₂.

Reaction corresponding to 4th option is H₂ + Cl₂ - > 2 HCl.

The iron and sulphur undergoes a redox reaction where the iron gets oxidized to ferrous ion and Sulphur gets reduced to sulphide ion. Its an addition reaction as well.

The mercury and oxygen undergoes a redox reaction which makes the oxygen to oxide ion and mercury to mercuric ions. Its an addition reaction as well.

The calcium and water undergoes a displacement reaction where the calcium removes the hydrogen from water forming calcium hydroxide and hydrogen gas.

The hydrogen and chlorine undergoes an addition reaction forming hydrogen chloride. Its also a redox reaction as well.

the answer is true when observing or determining population size, a direct observation is use, in which each organism is counted in a population or in an area. one benefit of this measure is that you get the exact population count but it will take a long time to  determine  the  size  of a  population.