In: Chemistry
For each of the questions below, choose the correct answer from the choices indicated (a), (b), (c) or (d).
(1) Assuming one atom per lattice point, a Simple Cubic structure when heated transforms to a Body Centered Cubic (BCC) structure. Assuming that the atomic radii remain the same, its mass density will increase by: (a) 30%; (b) 9%; (c) 4%; (d) 23%.
(2) Assuming one atom per lattice point, a Simple Cubic (SC) structure when heated transforms to a Face Centered Cubic (FCC) structure. Assuming that the atomic radii remain the same, its volume will decrease by: (a) 4%; (b) 9%; (c) 23%; (d) 29%.
(3) A Face Centered Close Packed (FCP) structure when heated transforms to a Hexagonal Close Packed (HCP) structure. Assuming that the atomic radii remain the same, its mass density will decrease by: (a) 9%; (b) 4%; (c) 30%; (d) 0%.
(4) A hypothetical AX type ceramic material has density of 2.65 g/cc and cubic structure with edgle length of 0.43 nm. The atomic weights of A and X elements are 86.6 and 40.3 g/mol respectively. The, AX has crystal structure similar to: (a) CsCl; (b) CaF2; (c) ZnS; (d) NaCl.
(5) Given the ionic radii: Na1+ = 0.102 nm and F1- = 0.133 nm, what is the ionic packing factor of NaF? (a) 52%; (b) 76%; (c) 72%; (d) 68%.
(6) Given the ionic radii: Mg2+ = 0.072 nm and O2- = 0.140 nm, what is the ionic packing factor of MgO? (a) 84%; (b) 80%; (c) 74%; (d) 69%.
(1) Assuming one atom per lattice point, a Simple Cubic structure when heated transforms to a Body Centered Cubic (BCC) structure. Assuming that the atomic radii remain the same, its mass density will increase by:
(a) 30%
(2) Assuming one atom per lattice point, a Simple Cubic (SC) structure when heated transforms to a Face Centered Cubic (FCC) structure. Assuming that the atomic radii remain the same, its volume will decrease by:
(c) 23%
(3) A Face Centered Close Packed (FCP) structure when heated transforms to a Hexagonal Close Packed (HCP) structure. Assuming that the atomic radii remain the same, its mass density will decrease by:
(b) 4%
(4) A hypothetical AX type ceramic material has density of 2.65 g/cc and cubic structure with edge length of 0.43 nm. The atomic weights of A and X elements are 86.6 and 40.3 g/mol respectively. The, AX has crystal structure similar to:
(a) CsCl
(5) Given the ionic radii: Na1+ = 0.102 nm and F1- = 0.133 nm, The ionic packing factor of NaF would be,
= [(4 x 3.14 x (0.102)^3/3) + (4 x 3.14 x (0.133)^3/3)]/[((2 x 0.102 + 2 x 0.133)/sq/rt(3))^3] x 100 = 72%
(c) 72%
(6) Given the ionic radii: Mg2+ = 0.072 nm and O2- = 0.140 nm, The ionic packing factor of MgO would be,
(a) 84%