How many grams of NaCl are there in 5.80 x 10^24 molecules of NaCl? (The molar mass of NaCl is 58.44 g/mol) Group of answer choices
5.63
563 g
56.3 g
5630 g
5.63 g

i do not get it   at all

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.