Which of the following is a single replacement reaction? Ca(OH)2 + H2SO4 → CaSO4 + 2H2O
CH4 + 2O2 → CO2 + 2H2O
H2O+ CO2 → H2CO3
Fe + 3NaBr → FeBr3 + 3Na

Fe + 3NaBr    →   FeBr₃ + 3Na

Explanation:

Single replacement:

It is the reaction in which one elements replace the other element in compound.

AB + C → AC + B

Chemical equation:

Fe + 3NaBr    →   FeBr₃ + 3Na

This chemical equation shows the single replacement reaction. Iron replace the sodium and react with bromine.

All other options are incorrect because,

Ca(OH)₂ + H₂SO₄      →     CaSO₄  + 2H₂O

It is double replacement reaction.

CH₄ + 2O₂     →     CO₂  + 2H₂O

This reaction equation shows combustion.

H₂O + CO₂  →    H₂CO₃

This is synthesis reaction.

The correct answer is D) Fe + 3NaBr → FeBr3 + 3Na

Explanation:

2fe + 3h2so4 -> fe2(so4)3 + 3h2

it is necessary to balance equations in order to get the proper amount of reactants as well as products in order not to make a miscalculation.

you cannot change the subscripts as that would change the substance itself. for instance, diatomic elements such as h2 only have the subscript two when a gas. another example would be so4, if you were to change the subscript, the element would no longer be sulfate.

we change the coefficients instead as that only changes the number of molecules rather than the substance itself.

hope this !

the maximum mass of nh3 is nh3 in grams