---
title: "A student tests four unknown crystalline solids in the laboratory to classify their bonding types and structures. The student records the observations and data in the table below.  | Substance | Melting point ( \\(^ \\circ\\text{C}\\)) | Electrical conductivity (solid) | Electrical conductivity (liquid) | | :— | :— | :— | :— | | W | \\(801\\) | Nonconductor | Good conductor | | X | \\(1085\\) | Good conductor | Good conductor | | Y | \\(1710\\) | Nonconductor | Nonconductor | | Z | \\(115\\) | Nonconductor | Nonconductor |  Based on the data in the table, which of the following correctly identifies one of the substances and provides the valid structural justification?"
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url: "https://nerd-notes.com/ubq/121380/"
date_modified: "2026-08-23T05:01:59+00:00"
---

# A student tests four unknown crystalline solids in the laboratory to classify their bonding types and structures. The student records the observations and data in the table below.

| Substance | Melting point (
\(^
\circ\text{C}\)) | Electrical conductivity (solid) | Electrical conductivity (liquid) |
| :— | :— | :— | :— |
| W | \(801\) | Nonconductor | Good conductor |
| X | \(1085\) | Good conductor | Good conductor |
| Y | \(1710\) | Nonconductor | Nonconductor |
| Z | \(115\) | Nonconductor | Nonconductor |

Based on the data in the table, which of the following correctly identifies one of the substances and provides the valid structural justification?

A student tests four unknown crystalline solids in the laboratory to classify their bonding types and structures. The student records the observations and data in the table below.

| Substance | Melting point (
\(^
\circ\text{C}\)) | Electrical conductivity (solid) | Electrical conductivity (liquid) |
| :--- | :--- | :--- | :--- |
| W | \(801\) | Nonconductor | Good conductor |
| X | \(1085\) | Good conductor | Good conductor |
| Y | \(1710\) | Nonconductor | Nonconductor |
| Z | \(115\) | Nonconductor | Nonconductor |

Based on the data in the table, which of the following correctly identifies one of the substances and provides the valid structural justification?

- **A.** Substance X is an ionic solid because its high melting point results from strong electrostatic attractions between oppositely charged ions that can move freely in the crystal lattice.
- **B.** Substance Y is a molecular solid because it does not conduct electricity in either state due to the presence of localized covalent bonds.
- **C.** Substance Z is a covalent network solid because its low melting point is due to relatively weak intermolecular forces between individual molecules.
- **D.** Substance W is an ionic solid because its ions are held in fixed lattice positions in the solid state but become mobile to carry electric current in the liquid state.

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/121380/*