How can a roman numeral in a chemical name be used to write a chemical formula?
A. The roman numeral is the charge on the nonmetal in the chemical
formula.
B. The roman numeral is the metal's oxidation state used as the
subscript on the nonmetal in the crisscross method.
C. The roman numeral is the nonmetal's oxidation state used as the
subscript on the metal in the crisscross method.
O D. The roman numeral is the subscript on the metal in the chemical
formula.

the answer is a! (2.9 x 10^-18 j) hope i could someone. : )

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.