A cylinder contains 68 g of ammonia gas at S.T.P.
How many moles of ammonia are present in the cylinder?

Explanation

To find the number of moles of ammonia (NH₃) present in the cylinder, we can use the formula:

\[ \text{Number of moles} = \frac{\text{Mass of substance (g)}}{\text{Molar mass of substance (g/mol)}} \]

### Step 1: Identify the mass of ammonia
The mass of ammonia given in the question is 68 grams.
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