About how many electrons are in 30 grams of water (H2O)? The answer is 10^25, i took a lucky guess i just want to know how to find that.

Aballet student who learns with the of his instructor is demonstrating learning.

Explain earth's motion, using the terms "precession" and "rotation" in your answer.

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.