Question

Which one of the following contains the highest number of oxygen atoms?

• A. One mole of aluminum sulphate
• B. Two moles of ferrous sulphate
• C. Three moles of hydrogen peroxide
• D. Two moles of potassium permanganate
• E. One mole of potassium dichromate

Answer 1

The Correct Option is A

Let's calculate the number of oxygen atoms in each compound:
Aluminum Sulphate (Al$_2$(SO$_4$)$_3$): One mole of aluminum sulphate contains 3 moles of sulphate ions (SO$_4^{2-}$), and each sulphate ion contains 4 oxygen atoms. Therefore, one mole of aluminum sulphate contains: \[ 3 \times 4 = 12 \, \text{moles of oxygen atoms} \]
Ferrous Sulphate (FeSO$_4$): Each mole of ferrous sulphate contains 1 mole of sulphate ions (SO$_4^{2-}$), and each sulphate ion contains 4 oxygen atoms. Therefore, two moles of ferrous sulphate contain: \[ 2 \times 4 = 8 \, \text{moles of oxygen atoms} \]
Hydrogen Peroxide (H$_2$O$_2$): One mole of hydrogen peroxide contains 2 moles of oxygen atoms. Therefore, three moles of hydrogen peroxide contain: \[ 3 \times 2 = 6 \, \text{moles of oxygen atoms} \]
Potassium Permanganate (KMnO$_4$): Each mole of potassium permanganate contains 4 moles of oxygen atoms. Therefore, two moles of potassium permanganate contain: \[ 2 \times 4 = 8 \, \text{moles of oxygen atoms} \] - Potassium Dichromate (K$_2$Cr$_2$O$_7$): Each mole of potassium dichromate contains 7 moles of oxygen atoms. Therefore, one mole of potassium dichromate contains: \[ 7 \, \text{moles of oxygen atoms} \] Thus, one mole of aluminum sulphate contains the highest number of oxygen atoms, with 12 moles of oxygen atoms. The correct answer is (1) One mole of aluminum sulphate.

The correct option is (A) : One mole of aluminum sulphate

Answer 2

Let's calculate the number of oxygen atoms in each compound:  

1. One mole of aluminum sulphate – Al₂(SO₄)₃:
Each SO₄ contains 4 O atoms, and there are 3 SO₄ groups:
→ 3 × 4 = 12 O atoms per molecule
→ In 1 mole: 12 × Avogadro's number oxygen atoms 

2. Two moles of ferrous sulphate – FeSO₄:
Each SO₄ has 4 O atoms
→ 4 × 2 = 8 O atoms per molecule × 2 moles = 8 O atoms per 2 molecules
→ In 2 moles: 8 × Avogadro's number oxygen atoms 

3. Three moles of hydrogen peroxide – H₂O₂:
Each H₂O₂ has 2 O atoms
→ 3 × 2 = 6 O atoms per 3 molecules
→ In 3 moles: 6 × Avogadro's number oxygen atoms 

4. Two moles of potassium permanganate – KMnO₄:
Each KMnO₄ has 4 O atoms
→ 2 × 4 = 8 O atoms
→ In 2 moles: 8 × Avogadro's number oxygen atoms 

5. One mole of potassium dichromate – K₂Cr₂O₇:
Each K₂Cr₂O₇ has 7 O atoms
→ In 1 mole: 7 × Avogadro's number oxygen atoms 

✅ Highest is 12 × Avogadro's number → One mole of aluminum sulphate