Answer:
There is 1 lead (Pb) element, 2 nitrogen (N) elements and 6 oxygen (O) elements.
Explanation:
Brackets in chemistry work the same like in maths. You multiply each element in the bracket depending on the power. In this case, we have a nitrogen atom and three oxygen atoms, in brackets, with a power of 2. You multiply the nitrogen atoms by 2, ending up with 2 nitrogen atoms, and you multiply the oxygen atoms by 2, ending up with 6.
