When long chains of carbon and hydrogen atoms break apart into smaller chains, the temperature decreases. Which type of reaction is this?
A. Exothermic
B. Endothermic
C. Replacement
D. Combustion

answer seismograph;

answer///carbon;

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.