The mass percentage of nitrogen in histidine is `"_________________"`.
[Atomic mass H=1,C =12, N = 14, O =16]

Explanation

To find the mass percentage of nitrogen in histidine, we will follow these steps:

### Step 1: Write the molecular formula of histidine.
Histidine has the molecular formula \( C_6H_9O_2N_3 \).

### Step 2: Identify the number of atoms of each element in histidine.
From the molecular formula, we can see:
- Carbon (C) = 6
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