Achemical formula is an expression used to represent

A chemical formula is an expression that shows the elements in a compound and the relative proportions of those elements.

Explanation:

If only one atom of a specific type is present, no subscript is used. For atoms that have two or more of a specific type of atom present, a subscript is written after the symbol for that atom

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.