What do these two changes have in common? making jam silver jewelry tarnishing

Select all that apply.

Both are chemical changes.
Both result in a different type of molecule than was there before.
Both conserve mass.
Both are caused by cooling.​

metric time was an attempt to create a standard unit of time based off of 10, but it never took off an is not included in the metric system (si)

hypostyle hall;

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.