NCEES Materials Science 2

Question 1

Which crystal defect is formed when an atom is missing from its lattice site?

Accepted Answer

Vacancy defect

Answer

A vacancy defect (Schottky defect in ionic crystals) occurs when an atom is missing from its normal lattice position.

Question 2

What is the primary strengthening mechanism in cold-worked metals?

Accepted Answer

Dislocation density increase

Answer

Cold working increases dislocation density, causing dislocations to impede each other's motion and thereby strengthening the metal.

Question 3

The elastic modulus of a material is best described as:

Accepted Answer

The ratio of stress to strain in the elastic region

Answer

Young's modulus (elastic modulus) is defined as the ratio of uniaxial stress to strain within the elastic (reversible) deformation range.

Question 4

Which type of polymer chain arrangement leads to the highest crystallinity?

Accepted Answer

Isotactic

Answer

Isotactic polymers, where all substituents are on the same side of the backbone, pack most efficiently and achieve the highest degree of crystallinity.

Question 5

In a eutectic binary alloy system, the eutectic reaction is best described as:

Accepted Answer

A single liquid transforming into two solids simultaneously

Answer

At the eutectic point, a single liquid phase transforms simultaneously into two distinct solid phases at a fixed temperature.

NCEES Practice Test

NCEES Practice Test

NCEES Materials Science 2