Atoms of which of the following elements will diffuse most rapidly in iron? (A) Mo (B) C (C) Cr (D) W

¿Es la deforestación un recurso natural, un problema o una solución?

Calculate the diffusion coefficient for copper in aluminum at $600^{\circ}\mathrm{C}$. Preexponential and activation energy values for this system are $6.5 \times 10^{-5} \mathrm{m^{2}/s}$ and 136,000 J/mol, respectively. (A) $5.7 \times 10^{-2} \mathrm{m^{2}/s}$ (B) $9.4 \times 10^{-17} \mathrm{m^{2}/s}$ (C) $4.7 \times 10^{-13} \mathrm{m^{2}/s}$ (D) $3.9 \times 10^{-2} \mathrm{m^{2}/s}$

Two isomers (A and B) of a given compound dimerize as follows:

$$\begin{array} { l } { 2 \mathrm { A } \longrightarrow \mathrm { A } _ { 2 } } \\ { 2 \mathrm { B } \longrightarrow \mathrm { B } _ { 2 } } \end{array}$$

Both processes are known to be second order in the reactant, and $k _ { 1 }$ is known to be $0.250\ \mathrm { L }\ \mathrm { mol } ^ { - 1 }\ \mathrm { s } ^ { - 1 }$ at $25 ^ { \circ } \mathrm { C }.$ In a particular experiment A, and B were placed in separate containers at $25 ^ { \circ } \mathrm { C } ,$ where $[ \mathrm { A } ] _ { 0 } = 1.00 \times 10 ^ { - 2 }\ \mathrm { M }$ and $[ \mathrm { B } ] _ { 0 } = 2.50 \times 10 ^ { - 2 }\ \mathrm { M } .$ After each reaction had progressed for 3.00 min, [A] = 3.00[B]. In this case the rate laws are defined as follows:

$$\text {Rate} = - \frac { d [ \mathrm { A } ] } { d t } = k _ { 1 } [ \mathrm { A } ] ^ { 2 } \\ \text {Rate} = - \frac { d [ \mathrm { B } ] } { d t } = k _ { 2 } [ \mathrm { B } ] ^ { 2 }$$

Calculate the value of $k _ { 2 }.$

What is the composition, in weight percent, of an alloy that consists of 94.1 at% Ag and 5.9 at% Cu? The atomic weights for Ag and Cu are 107.87 g/mol and 63.55 g/mol, respectively. (A) 9.6 wt% Ag and 90.4 wt% Cu (B) 3.6 wt% Ag and 96.4 wt% Cu (C) 90.4 wt% Ag and 9.6 wt% Cu (D) 96.4 wt% Ag and 3.6 wt% Cu

describe how to transform the graph of ƒ into the graph of g.

$$f(x)=I2xIand g(x)=4IxI$$

The first two terms of the arithmetic sequence are given. Find the missing term. Use the table feature of a graphing utility to verify your results. $a_{1}=-0.7, \quad a_{2}=-13.8, \quad a_{8}= ?$

What is the composition, in atom percent, of an alloy that consists of $4.5 ~\text{wt} \%$ Pb and $95.5 ~\text{wt} \%$ Sn? The atomic weights for Pb and Sn are 207.19 g/mol and 118.71 g/mol, respectively.

(A) 2.6 at% Pb and 97.4 at% Sn

(B) 7.6 at% Pb and 92.4 at% Sn

(C) 97.4 at% Pb and 2.6 at% Sn

(D) 92.4 at% Pb and 7.6 at% Sn

For a BCC single crystal, would you expect the surface energy for a (100) plane to be greater or less than that for a (110) plane? Why?

Sketch the graph of each of the following functions: $y=\cos x$

Niobium (Nb) has a BCC crystal structure, an atomic radius of 0.143 nm, and an atomic weight of 92.91 g/mol.

What is the theoretical density for Nb?

The perimeter of an isosceles triangle is 4 times the length of the shortest side. The longer sides are 4.5 ft longer than the shortest side. What is the length of each side of the triangle?

Evaluate the given integral using the substitution (or method) indicated. $\int e^{x / 2} d x$; u=x/2

Calculate the number of vacancies per cubic meter at $1000^{\circ} \mathrm{C}$ for a metal that has an energy for vacancy formation of $1.22 \mathrm{~eV/atom}$, a density of $6.25 \mathrm{~g} / \mathrm{cm}^{3}$, and an atomic weight of $37.4 \mathrm{~g/mol}$.

(A) $1.49 \times 10^{18} \mathrm{~m}^{-3}$

(B) $7.18 \times 10^{22} \mathrm{~m}^{-3}$

(C) $1.49 \times 10^{24} \mathrm{~m}^{-3}$

(D) $2.57 \times 10^{24} \mathrm{~m}^{-3}$