Arrange compounds in each set according to specified order and give reasons for your answer.
Increasing order of solubility in water.
`C_(6)H_(5)CH_(2)OCH_(3), C_(6)H_(5)CH_(2)CH_(2)CH_(3),`
`p-CH_(3)C_(6)H_(4)COOH, p-OHC_(6)H_(4)CH_(2)OH`

Explanation

To determine the increasing order of solubility in water for the given compounds, we need to analyze their structures and the factors that influence their solubility. The compounds provided are:

1. **C₆H₅CH₂OCH₃** (an ether)
2. **C₆H₅CH₂CH₂CH₃** (an aromatic hydrocarbon)
3. **p-CH₃C₆H₄COOH** (p-toluic acid, an aromatic carboxylic acid)
4. **p-OHC₆H₄CH₂OH** (p-hydroxybenzyl alcohol, an aromatic alcohol)

### Step 1: Analyze each compound's structure and polarity
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