Which of the following are decomposition reactions? ch4 (g) + o2 (g) → co2 (g) + h2o (l) cao (s) + co2 (g) → caco3 (s) mg (s) + o2 (g) → mgo (s) pbco3 (s) → pbo (s) + co2 (g)

The correct answer is D. PbCO3 (s) → PbO (s) + CO2 (g)

Explanation:

In chemistry, a reaction occurs as substances, elements or compounds interact or change and lead to products or substances that are different from the original ones. In the case of decomposition reactions, this occurs when the one substance or compound leads to two or more products after the reaction and thus, it can be represented as AB → A + B. This type of reaction is the one that occurs in PbCO3 (s) → PbO (s) + CO2 (g) because Lead Carbonate or PbCO3 that is the original reactant leads to two products Lead (II) Oxide or PbO and Carbon dioxide or CO2.

the seeing the electronic configuration we can say that the element is fluorine.

fluorine is the most electronegative element in the periodic table.

but by only seeing the configuration we cannot say about its reactivity because we don't know if its configuration after excitation or by addition of electrons.

but if not then, it is the lightest halogen and exists as a highly toxic pale yellow diatomic gas at standard conditions. as the most electronegative element, it is extremely reactive: almost all other elements, including some noble gases, form compounds with fluorine.