We are asked to identify what type of rock would be formed in a plant-rich swamp. We all know that plant dies and the remain leaves in the soil called peat. Temperature, pressure and heat causes the remains to submerged under the soil bed layer and converts it into a waxy substance called kerogen. Kerogen then mixes with the rock under the soil bed layer to create what is called an oil shale. Oil shale is somehow similar to a coal. Both creates an energy when ignited. Therefore the correct answer to the question being asked is COAL or Oil Shale.
This question is asking for an element with 5 valence electrons. Just go to the row it is in (excluding transition metals) and count over.
The answer would be c. P
Answer:
The type of reaction for the following equation is combustion equation.
Explanation:
Combustion reaction is defined as the chemical reaction in which a hydrocarbon reacts with oxygen gas to produce carbon dioxide gas and water molecule.

The reaction given to us:

When 1 mole of ethane reacts with 7/2 moles of oxygen gas it gives 3 moles of water and 2 moles of carbon dioxide gas.
The type of reaction for the following equation is combustion equation.