When each of the nitrates of Potassium, Magnesium and iron is heated,
A
all the nitrates decompose to their oxides
B
the nitrate of magnesium gives the nitrite and oxygen
C
the nitrates of magnesium and iron give the oxides
D
the nitrate of iron gives the nitrite and oxygen
E
the nitrate of the magnesium is not decomposed
Verified Correct Answer: C.
Chemical Principles & Mechanism
When heated, the nitrates of potassium, magnesium, and iron decompose as follows:
- Potassium nitrate (KNO₃) decomposes to potassium nitrite (KNO₂) and oxygen (O₂).
- Magnesium nitrate (Mg(NO₃)₂) decomposes to magnesium oxide (MgO) and nitrogen dioxide (NO₂) and oxygen (O₂).
- Iron(III) nitrate (Fe(NO₃)₃) decomposes to iron(III) oxide (Fe₂O₃) and nitrogen dioxide (NO₂) and oxygen (O₂).
So, all three nitrates would not decompose to their respective oxides except Nitrates of Magnesium and Iron.
The correct answer is C.
Source: Myschool Past Questions Archive (Record #50)