Q. Structure test of NaOH.

To find the structure of NaOH, we identify its chemical formula and then translate it into how the atoms are arranged in matter.

Step 1: Identify the formula

The chemical formula NaOH tells us the substance contains three parts:

• \( \text{Na} \): sodium
• \( \text{O} \): oxygen
• \( \text{H} \): hydrogen

So, the substance is made from the ions (in ionic compounds):

• \( \text{Na}^+ \)
• \( \text{OH}^- \) (the hydroxide ion)

Step 2: Write the ionic structure (how it exists in solid sodium hydroxide)

In ionic compounds, the most useful “structure” description is based on ions held together by electrostatic attraction.

Sodium hydroxide consists of alternating ions:

• positively charged sodium ions \( \text{Na}^+ \)
• negatively charged hydroxide ions \( \text{OH}^- \)

Therefore, the crystal lattice can be described as a repeating pattern of \( \text{Na}^+ \) and \( \text{OH}^- \) units held by ionic forces.

Step 3: Describe the hydroxide ion geometry

The key structural unit inside NaOH is the hydroxide ion \( \text{OH}^- \).

The hydroxide ion has a simple molecular shape:

• It contains one oxygen and one hydrogen atom.
• In the ion, the oxygen is the center with hydrogen attached.

Because there are only two atoms, the ion is linear (an oxygen-hydrogen bond), and the structure is simply:

\[
\text{O–H}
\]

Step 4: Final structural summary

So the structure of NaOH can be stated in two common, correct ways:

1) Ionic representation (most standard for NaOH):

\[
\text{NaOH} \rightarrow \text{Na}^+ + \text{OH}^-
\]

2) Structural unit within the ionic compound:

\[
\text{OH}^- \text{ consists of an O atom bonded to an H atom}
\]

Answer (structure of NaOH): NaOH is an ionic compound made of \( \text{Na}^+ \) ions and \( \text{OH}^- \) (hydroxide) ions, with the hydroxide ion having an \( \text{O–H} \) bond. In solid form, these ions arrange into a lattice through electrostatic attraction.