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ISRO 2016 Mechanical Engineering Questions, Answers and Explanation

ISRO 2016 Mechanical Engineering Questions, Answers and Explanation

 54. Which of the following order of crystal structure will match with metals Iron - Copper - Zinc in that order?
a) BCC - FCC - HCP
b) FCC - BCC - HCP
c) HCP - FCC - BCC
d) BCC - FCC - HCP

 Answer
d) BCC - FCC - HCP

 Explanation [Material Science]
BCC - Lithium (Li), Sodium (Na), Potassium (K), Rubidium (Rb), Barium (Ba), Vanadium (V), Chromium (Cr), Iron (Fe).
The bcc arrangement does not allow the atoms to pack together as closely as the fcc or hcp arrangements. Metals which have a bcc structure are usually harder and less malleable than close-packed metals such as gold. When the metal is deformed, the planes of atoms must slip over each other, and this is more difficult in the bcc structure. 
FCC - Aluminium (Al), Copper(Cu), Gold (Au), Iridium (Ir), Lead(Pb), Nickel (Ni), Platinum (Pt), Silver (Ag).
HCP - Beryllium(Be), Cadmium (Cd), Magnesium (Mg), Titanium (Ti), Zinc (Zn), Zirconium (Zr)

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