Question

The correct decreasing order of oxidation state of the underlined atom in each molecule is

• A. \(P_4O_{10} \gt Cl_2O_7 \gt AlH_3\)
• B. \(P_4O_{10} \gt SO_3 \gt H_2O\)
• C. \(N_2O_5 \gt Al_2O_3 \gt H_2S\)
• D. \(PbO_2 \gt N_2O_3 \gt SO_3\)

Hint:

For neutral compounds, the algebraic sum of oxidation numbers of all atoms is always zero. Use this rule systematically to determine unknown oxidation states.

Answer 1

The Correct Option is C

Step 1: Determine oxidation state of nitrogen in \(N_2O_5\). Let oxidation state of nitrogen be \(x\). \[ 2x+5(-2)=0 \] \[ 2x-10=0 \] \[ x=+5 \]

Step 2: Determine oxidation state of aluminium in \(Al_2O_3\). Let oxidation state of aluminium be \(x\). \[ 2x+3(-2)=0 \] \[ 2x-6=0 \] \[ x=+3 \]

Step 3: Determine oxidation state of sulphur in \(H_2S\). Let oxidation state of sulphur be \(x\). \[ 2(+1)+x=0 \] \[ x=-2 \]

Step 4: Arrange in decreasing order. \[ +5 \gt +3 \gt -2 \] Therefore, \[ N_2O_5 \gt Al_2O_3 \gt H_2S \] Hence the correct answer is \[ \boxed{(C)} \]