Identify the elements M (atomic number 8) and N (atomic number 15) and describe the nature of their oxides, including a reaction with water if applicable.

Step 1: Identify the elements M and N.
Element M has an atomic number of 8, which is Oxygen ($\text{O}$).
Element N has an atomic number of 15, which is Phosphorus ($\text{P}$).

Step 2: Determine the nature of their oxides.

• For element N (Phosphorus), a common oxide is phosphorus(V) oxide ($\text{P}_4\text{O}_{10}$). This is an acidic oxide. When it reacts with water, it forms phosphoric acid: $$$$