What is the percent of phosphorus by mass in phosphoric acid,
H3PO4? Use 1008 g/mol for the molar mass of hydrogen, 16.00
g/mol for the molar mass of oxygen, and 30.97 g/mol for the
molar mass of phosphorus.

geosphere and hydrosphere.

this is because the geosphere has to do with geological events, while the hydrosphere controls all water on earth.

answer: semi-infinite solid initially at a uniform temperature of 400 ◦c is cooled at its surface by convection. the cooling fluid at a constant temperature of 200 ◦c has a convective coefficient (ha) of 250 w/m2.k. the physical properties of the solid: k = 20 w/m.k and α = 4 * 10-5  m2/s. using δx = 0.04 m and δt = 10 s. write the finite difference equations describing the transient heat transfer of the first five δx and the temperature profile after 30 s.