Day 1 Refresher

Question 1

which of the ff is true of reversible processes

a. they are always spontaneous
b. they increase entropy
c. they occur without energy loss
d. they occur rapidly

Answer 1

they occur without energy loss

Question 2

Bond energy is generally highest for which type of bonding?
a. Metallic c. Covalent
b. Ionic d. Hydrogen

Answer 2

covalent

metallic- lowest

Question 3

What type of bond is found between carbon atoms in diamond?
a. ionic c. non-polar covalent
b. polar covalent d. metallic

Answer 3

non polar covalent

polar covalent - no difference in electronegativity

diamond - C-C-C-C

Question 4

Which bond type is typically associated with the highest melting points?
a. Hydrogen bonding c. Metallic bonding
b. Ionic bonding d. van der Waals bonding

Answer 4

ionic bonding

Question 5

The coordination number of atoms in a face-centered cubic (FCC)
crystal lattice is:
a. 4 c. 12
b. 6 d. 14

Answer 5

12

Question 5

Which element pairing would produce a bond with the highest ionic
character?
a. C and H c. Na and Cl
b. O and N d. Si and P

Answer 5

Na and Cl

ionic character is propor to difference in electronegativity

Question 5

In nylon and proteins, what secondary bonding contributes to structure
and stability?
a. Ionic bonding c. Hydrogen bonding
b. Dipole-dipole d. Metallic bonding

Answer 5

hydrogen binding

secondary has no electron sharing
primary covalent

Question 5

Which crystal system has three unequal axes, all at right angles?
a. Tetragonal c. Monoclinic
b. Orthorhombic d. Triclinic

Answer 5

orthorhombic

Question 6

Why is the face-centered cubic (FCC) structure more densely packed
than body-centered cubic (BCC)?
a. FCC has larger atoms
b. FCC has higher atomic mass
c. FCC atoms are arranged to occupy more volume
d. FCC has atoms at face centers, increasing packing efficiency

Answer 6

FCC has atoms at face centers, increasing packing efficiency

apf means more packed w/c means denser

Question 7

Which of the following correctly ranks crystal structures by atomic
packing factor (APF), from highest to lowest?
a. BCC > FCC > Simple cubic c. Simple cubic > FCC > BCC
b. FCC > BCC > Simple cubic d. HCP > FCC > BCC

Answer 7

FCC > BCC > Simple cubic

Question 8

Which metal is known to have an HCP structure and poor ductility at
room temperature?
a. Lead c. Zinc
b. Iron d. Copper

Answer 8

zinc

Question 9

What do Miller indices represent?
a. Interatomic spacing
b. Crystal defects
c. Crystallographic planes and directions
d. Bond energy levels

Answer 9

Crystallographic planes and directions

miller indices para makuha ang

Question 10

Which Miller index represents a plane that cuts the x-axis at 1 and is
parallel to y and z axes?
a. (1 0 0) c. (1 1 1)
b. (0 1 1) d. (1 0 1)

Answer 10

(1 0 0)

Question 11

In X-ray diffraction, the condition nλ = 2d sin θ represents:
a. Laue equation c. Fick’s first law
b. Bragg’s law d. Hall–Petch relation

Answer 11

Bragg’s Law

gina gamitan ka miller index ang XRD

Question 12

For BCC iron, compute the interplanar spacing if the lattice parameter
for Fe is 0.2866 nm.
a. 0.1 nm c. 0.3 nm
b. 0.2 nm d. 0.4 nm

miller index: (2 2 0)

Answer 12

0.1 nm

Question 13

The metal niobium has a BCC crystal structure. If the angle of
diffraction for the (211) set of planes occurs at 75.99 degrees (first order
reflection) when monochromatic x-radiation having a wavelength of
0.1659 nm is sued, compute the interplanar spacing for the niobium atom.
a. 0.13 nm c. 0.25 nm
b. 0.38 nm d. 0.44 nm

Answer 13

0.13 nm

Question 14

The term anisotropy in crystalline materials indicates that:
a. Properties are the same in all directions
b. Properties vary with crystallographic direction
c. Material contains glassy regions
d. Defect density is uniform

Answer 14

Properties vary with crystallographic direction

Question 15

The glass transition temperature is most relevant for:
a. Metals c. Ceramics
b. Amorphous polymers
d. Crystalline polymers

Answer 15

Amorphous polymers

crystalline - inorder (may pattern)
amorphous - disorder

Question 15

Schottky defects in ionic crystals involve:
a. A cation vacancy paired with an interstitial cation
b. A paired set of cation and anion vacancies
c. An anion vacancy and adjacent electron in the lattice
d. Dislocation loops around impurity atoms

Answer 15

A paired set of cation and anion vacancies

Question 15

Which combination of defects leads to improved mechanical strength
in alloys?
a. Grain boundaries and dislocations
b. Vacancies and interstitials
c. Phase separation and substitutional atoms
d. Voids and Frenkel defects

Answer 15

Grain boundaries and dislocations

line defect
b-d are point defects

Question 16

A screw dislocation is characterized by:
a. Burgers vector perpendicular to the dislocation line
b. Burgers vector parallel to the dislocation line
c. Absence of shear stress field
d. Rotation of crystal planes around a vacancy core

Answer 16

Burgers vector parallel to the dislocation line

recheck

Question 16

Which crystal defect is classified as a line defect?
a. Vacancy c. Schottky defect
b. Interstitial atom d. Edge dislocation

Answer 16

edge dislocation

Question 17

Stacking fault energy (SFE) is lowest in which metal, leading to
extensive twinning during deformation?
a. Aluminum c. Nickel
b. Copper d. Magnesium

Answer 17

copper

Question 18

Which of the following is a common eutectic alloy?
a. Brass c. Lead-tin solder
b. Stainless steel d. Bronze

Answer 18

lead-tin solder

eutectic - ie soldering - liquid form 2 diff solids
eutectic point 61.9

Question 19

The eutectic reaction in the Pb-Sn phase diagram can be written as: a. α → β + L c. γ → α + L b. L → α + β d. L → γ

Question 20

What is a eutectic point in a binary phase diagram? a. The point where solubility is zero b. The point with the highest melting temperature c. The composition and temperature where both components solidify simultaneously d. The pressure at which vaporization occurs | eutectic point 61.9

Answer 20

The composition and temperature where both components solidify simultaneously

Question 20

If a 50-50 wt% Pb-Sn alloy is cooled slowly from the liquid phase and the eutectic composition is 61.9% Sn, what phases form first? a. Pb solid c. Eutectic structure b. Sn solid d. Liquid solution

Answer 20

Pb solid | eutectic point 61.9

Question 21

Why is the eutectic alloy often preferred for casting? a. It forms ductile grains b. It solidifies over a wide temperature range c. It provides the lowest melting point and sharp solidification d. It prevents oxidation

Question 21

In a peritectic alloy, what happens during slow cooling through the peritectic temperature? a. Liquid remains until solidification b. A new solid phase grows from the liquid and existing solid c. Solid transforms directly to another solid d. Two solid phases melt

Answer 21

| peritectic liqd + solid 1 = solid 2