Decomposition of `NH_(3)` on the surface of tungsten is a reaction of :

Options

A. zero order
B. first order
C. second order
D. fractional order.

Explanation

To determine the order of the reaction for the decomposition of ammonia (NH₃) on the surface of tungsten, we can follow these steps:

### Step 1: Identify the Reaction
The decomposition of ammonia can be represented by the balanced chemical equation:
\[ 2 \text{NH}_3(g) \rightarrow \text{N}_2(g) + 3 \text{H}_2(g) \]

### Step 2: Recognize the Role of Tungsten
Tungsten acts as a catalyst in this reaction. Since tungsten is a solid and ammonia is a gas, this reaction is an example of heterogeneous catalysis. Heterogeneous catalysis occurs when the catalyst and the reactants are in different phases.

### Step 3: Understand the Characteristics of Heterogeneous Catalysis
In general, reactions that involve heterogeneous catalysis are often zero-order reactions. This is because the rate of reaction is independent of the concentration of the reactants when the catalyst is in excess.

### Step 4: Conclude the Order of the Reaction
Since the decomposition of ammonia on the surface of tungsten is a reaction involving heterogeneous catalysis, we conclude that it is a zero-order reaction.

### Final Answer
The decomposition of NH₃ on the surface of tungsten is a zero-order reaction.

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