Based on information from the periodic table, which statement is true for the element cobalt?
27
Co
58.9
A. A cobalt atom contains 27 protons, and most cobalt atoms
contain 32 neutrons.
B. A cobalt atom contains 27 protons, and neutral cobalt atoms
contain 32 electrons.
C. The atomic number of cobalt is 27, and its average atomic mass is
32
D. The average atomic number of cobalt is 58.9, and its atomic mass
is 27.

The coefficient of friction is a number that represents the resistance to sliding between two in contact with one another.

Asheet of steel 1.5 mm thick has nitrogen atmospheres on both sides at 1200oc and is permitted to achieve a steady-state diffusion condition. the diffusion coefficient for nitrogen in steel at this temperature is 6 x 10- 11 m2 /s, and the diffusion flux is found to be 1.2 x 10-7 kg/m2 -s. also, it is known that the concentration of nitrogen in the steel at the high-pressure surface is 4 kg/m3 . how far into the sheet from this high-pressure side will the concentration be 2.0 kg/m3 ? assume a linear concentration profile.

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