An oxide of nitrogen that can rekindle a glowing splint is

Analysis

The question asks for an oxide of nitrogen that has the ability to support combustion (rekindle a glowing splint). In chemistry, a substance that rekindles a glowing splint is typically an oxidizing agent that decomposes to release oxygen gas ($O_2$).

Concept Explanation

To solve this, we must look at the chemical properties of nitrogen oxides:

1. Nitrogen(I) oxide ($N_2O$): Also known as nitrous oxide or "laughing gas." It is a neutral oxide. When heated, it decomposes into nitrogen and oxygen: $$2N_2O(g) \rightarrow 2N_2(g) + O_2(g)$$ Because it releases oxygen upon decomposition, it supports combustion and can rekindle a glowing splint.
2. Nitrogen(II) oxide ($NO$): A neutral oxide that is colorless. It reacts readily with oxygen to form nitrogen(IV) oxide ($NO_2$) but does not spontaneously decompose to release oxygen in a way that supports a glowing splint.
3. Nitrogen(IV) oxide ($NO_2$): A reddish-brown, acidic gas. It is a strong oxidizing agent, but it does not decompose to release oxygen as readily as $N_2O$ under the conditions required to rekindle a glowing splint.
4. Dinitrogen tetraoxide ($N_2O_4$): This is the dimer of nitrogen(IV) oxide. It shares similar chemical properties with $NO_2$ and does not act as a source of oxygen for a glowing splint.

Step-by-Step Solution

• Step 1: Identify the requirement. A glowing splint rekindles in the presence of oxygen. Therefore, we are looking for an oxide that decomposes to produce oxygen gas.
• Step 2: Evaluate the thermal stability of the options. Nitrogen(I) oxide ($N_2O$) is known to be thermally unstable at high temperatures.
• Step 3: Write the decomposition equation. As shown above, $2N_2O \rightarrow 2N_2 + O_2$. The production of $O_2$ is the key factor here.

Conclusion

Nitrogen(I) oxide ($N_2O$) is the only oxide among the options that effectively decomposes to supply the oxygen necessary to rekindle a glowing splint.

Exam Tip: Always remember the "Neutral Oxides" of nitrogen: $N_2O$ and $NO$. Among these, $N_2O$ is the one famous for its ability to support combustion, similar to how oxygen gas ($O_2$) behaves.