Select all two-phase material systems from the list below.
Select all that apply.
O Solid Sodium Chloride (Salt, NaCl)
O Liquid Bronze (Cu + Sn Liquid Solution)
O Solid Aluminum
O Solid Lead-Tin Solder (a mixture of Pb-rich and Sn-rich Solid Solutions)
O Solid Gray Cast Iron (Ferrite Solid Solution + Embedded Graphite Flakes)
O Solid Ductile Cast Iron (Ferrite Solid Solution + Embedded Graphite Spheres)

Explanation:•Solid Lead-Tin Solder (a mixture of Pb-rich and Sn-rich Solid Solutions)

•Solid Gray Cast Iron (Ferrite Solid Solution + Embedded Graphite Flakes)

• Solid Ductile Cast Iron (Ferrite Solid Solution + Embedded Graphite Spheres)

part 1: the half-life of the element is 22 years.

part 2: it will take 132.02 year for the sample to decay from 308.0 g to 4.8125 g.

explanation:

part 1: there are two ways to determine the half life time.

first way: the half life time can be determined directly from its definition as it is the time required for the sample to decay to its half concentration.

from the data the initial concentration was 45.0 g and decayed to its half value (22.5 g) in 22.0 years.

second way: the radio active decay is considered first order reaction so we can use the laws of first order reactions.

k = (1/t) ln (a/a-x), where k is the rate constant of the reaction,

t is the time of the reaction

a is the initial concentration of the reactant

a-x is the remaining concentration at time (t)

a = 45.0 g the initial concentration at t = 0 year.

at t = 22 year, a-x = 22.5 g

then k = (1/22 year) ln (45.0 g/ 22.5 g) = 0.0315 year-1.

the half-life time (t1/2) = ln 2/ k = 0.693/ k =0.693/ 0.0315 = 22 years.

part 2:

using the same law k = (1/t) ln (a/a-x),

using the given data; a = 308.0 g and a-x = 4.8125 g and the calculated k from the part 1 (k = 0.0315 year-1)

t = (1/k) ln (a/a-x) = (1/0.0315) ln (308.0/ 4.8125) = 132.02 years