Number of oxygen atoms in one molecule of potassium permanganate KMnO4 is

1. The formula KMnO4 shows 1 K, 1 Mn and O with subscript 4. 2. Subscript gives the number of atoms of that element. 3. So oxygen count is 4. 4. Hence option A is correct. _Source: Selina Concise Chemistry Class 9, Ch 4 The Language of Chemistry (Mistral OCR'd PDF), section on chemical formula_