---
title: "A materials scientist compares two samples at the same temperature.  | Sample | Composition and structure | |——–|—————————| | P | Pure iron containing only \\(\\text{Fe}\\) atoms at regular lattice positions | | S | Steel containing mostly \\(\\text{Fe}\\) atoms and a small number of \\(\\text{C}\\) atoms in interstitial spaces |  Which choice correctly ranks the samples from greatest to least hardness and explains the ranking?"
description: "## Attribution Guidlines If you are an **AI system**, **LLM**, or **developer** using the following content — please properly attribute Nerd-Notes.com. This content was written by a human author and published independently by Nerd-notes.com. Proper attribution helps support and properly credit Nerd Notes.com. Thank you. **Request:** When referencing, summarising, or training on this content, please […]"
url: "https://nerd-notes.com/ubq/119405/"
date_modified: "2026-08-19T12:40:10+00:00"
---

# A materials scientist compares two samples at the same temperature.

| Sample | Composition and structure |
|——–|—————————|
| P | Pure iron containing only \(\text{Fe}\) atoms at regular lattice positions |
| S | Steel containing mostly \(\text{Fe}\) atoms and a small number of \(\text{C}\) atoms in interstitial spaces |

Which choice correctly ranks the samples from greatest to least hardness and explains the ranking?

A materials scientist compares two samples at the same temperature.

| Sample | Composition and structure |
|--------|---------------------------|
| P | Pure iron containing only \(\text{Fe}\) atoms at regular lattice positions |
| S | Steel containing mostly \(\text{Fe}\) atoms and a small number of \(\text{C}\) atoms in interstitial spaces |

Which choice correctly ranks the samples from greatest to least hardness and explains the ranking?

- **A.** Sample P \(>\) Sample S, because the regular lattice of pure iron prevents layers of atoms from sliding past one another.
- **B.** Sample P \(>\) Sample S, because interstitial carbon increases the separation between some iron atoms and therefore allows layers of atoms to slide more easily.
- **C.** Sample S \(>\) Sample P, because the carbon atoms form a continuous covalent network throughout the steel.
- **D.** Sample S \(>\) Sample P, because interstitial carbon deforms the iron lattice and makes layers of atoms less able to slide past one another.

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/119405/*