What is the chemical formula for iron(II) phosphate? A) Fe3P2 B) Fe3(PO4)2 C) Fe2PO4 D) Fe2P 2) What is the charge on the Cr in the ionic compound Cr2O3? A) 1+ B) 3+ C) 2+ D) 2- 3) The formula for dinitrogen trioxide is A) (NO3)2 B) N(OH)3. C) N2O3. D) N302
The Correct Answer and Explanation is :
1) What is the chemical formula for iron(II) phosphate?
Correct answer: B) Fe₃(PO₄)₂
Explanation:
Iron(II) phosphate refers to a compound containing iron with a +2 charge (Fe²⁺) and phosphate ions (PO₄³⁻). In the formula, the charges must balance, so you need to determine how many of each ion are required to balance the overall charge.
- The charge of Fe²⁺ is +2, and the charge of PO₄³⁻ is -3.
- To balance the charges, you need 3 iron ions (Fe²⁺) to counteract the 2 phosphate ions (PO₄³⁻), because 3 × (+2) = +6 and 2 × (-3) = -6. This gives a neutral overall charge.
- Therefore, the correct formula is Fe₃(PO₄)₂.
2) What is the charge on the Cr in the ionic compound Cr₂O₃?
Correct answer: B) 3+
Explanation:
In Cr₂O₃, chromium (Cr) is paired with oxygen (O). Oxygen typically has a charge of -2 (as in O²⁻). Since there are 3 oxygen atoms, the total charge from oxygen is 3 × (-2) = -6.
To balance this charge, the total positive charge from the two chromium ions must be +6.
Since there are 2 chromium ions, each must have a charge of +3, so the charge on Cr in Cr₂O₃ is +3. Therefore, the correct charge on chromium is 3+.
3) The formula for dinitrogen trioxide is:
Correct answer: C) N₂O₃
Explanation:
Dinitrogen trioxide is a molecular compound made up of nitrogen and oxygen. The prefix “di-” indicates two nitrogen atoms, and the prefix “tri-” indicates three oxygen atoms. Therefore, the correct molecular formula is N₂O₃. This is a simple compound with two nitrogen atoms and three oxygen atoms.
- Option A (NO₃)₂ refers to the nitrate ion (NO₃⁻), not dinitrogen trioxide.
- Option B (N(OH)₃) refers to a different nitrogen compound, possibly a hydroxide.
- Option D (N₃O₂) is an incorrect ratio of nitrogen and oxygen for dinitrogen trioxide.
Therefore, the correct molecular formula is N₂O₃.