Which of the following are deliquescent?
`NaCl, NaOH, Na_2CO_3, NaHCO_3`

Explanation

To determine which of the given compounds are deliquescent, we need to understand what deliquescent substances are. Deliquescent substances are those that absorb moisture from the atmosphere and can dissolve in the absorbed water, forming a solution.

Let's analyze each of the compounds provided:

1. **NaCl (Sodium Chloride)**:
- Sodium chloride is not deliquescent. It does absorb some moisture but does not dissolve in the absorbed moisture to form a solution. It remains as solid crystals.

2. **NaOH (Sodium Hydroxide)**:
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