---
title: "A student conducts a series of tests on four pure, crystalline solid substances, labeled \\(W\\), \\(X\\), \\(Y\\), and \\(Z\\). The observations and experimental data are recorded in the table below.  | Substance | Melting point (\\(^\\circ\\text{C}\\)) | Electrical conductivity of solid | Electrical conductivity of molten liquid | Solubility in water | | :— | :— | :— | :— | :— | | \\(W\\) | \\(119\\) | Nonconductor | Nonconductor | Insoluble | | \\(X\\) | \\(776\\) | Nonconductor | Good conductor | Soluble | | \\(Y\\) | \\(1713\\) | Nonconductor | Nonconductor | Insoluble | | \\(Z\\) | \\(660\\) | Good conductor | Good conductor | Insoluble |  Based on the data in the table, which of the following claims is best supported by the evidence?"
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url: "https://nerd-notes.com/ubq/123466/"
date_modified: "2026-09-28T11:59:51+00:00"
---

# A student conducts a series of tests on four pure, crystalline solid substances, labeled \(W\), \(X\), \(Y\), and \(Z\). The observations and experimental data are recorded in the table below.

| Substance | Melting point (\(^\circ\text{C}\)) | Electrical conductivity of solid | Electrical conductivity of molten liquid | Solubility in water |
| :— | :— | :— | :— | :— |
| \(W\) | \(119\) | Nonconductor | Nonconductor | Insoluble |
| \(X\) | \(776\) | Nonconductor | Good conductor | Soluble |
| \(Y\) | \(1713\) | Nonconductor | Nonconductor | Insoluble |
| \(Z\) | \(660\) | Good conductor | Good conductor | Insoluble |

Based on the data in the table, which of the following claims is best supported by the evidence?

A student conducts a series of tests on four pure, crystalline solid substances, labeled \(W\), \(X\), \(Y\), and \(Z\). The observations and experimental data are recorded in the table below.

| Substance | Melting point (\(^\circ\text{C}\)) | Electrical conductivity of solid | Electrical conductivity of molten liquid | Solubility in water |
| :--- | :--- | :--- | :--- | :--- |
| \(W\) | \(119\) | Nonconductor | Nonconductor | Insoluble |
| \(X\) | \(776\) | Nonconductor | Good conductor | Soluble |
| \(Y\) | \(1713\) | Nonconductor | Nonconductor | Insoluble |
| \(Z\) | \(660\) | Good conductor | Good conductor | Insoluble |

Based on the data in the table, which of the following claims is best supported by the evidence?

- **A.** Substance \(W\) has a relatively low melting point because melting requires breaking weak covalent bonds within individual molecules, leaving neutral particles that do not conduct electricity in the liquid phase.
- **B.** Substance \(Z\) consists of positive metal ions surrounded by a sea of mobile valence electrons in both solid and liquid states, whereas substance \(X\) consists of ions held in fixed lattice positions in the solid that become mobile charge carriers only upon melting.
- **C.** Substance \(X\) is a network covalent solid because its high melting point results from strong covalent bonds, and its molten liquid conducts electricity due to the release of delocalized electrons from the network.
- **D.** Substance \(Y\) is an ionic solid because its high melting point and water insolubility arise from exceptionally strong Coulombic attractions between oppositely charged ions that prevent dissolution.

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/123466/*