Which statement correctly describes what atoms and molecules are made of?
о
A. Atoms are made of molecules, and molecules are made of
protons, neutrons, and electrons.
B. Molecules are made of protons and neutrons, and atoms are
made of electrons and protons.
C. Atoms are made of protons and electrons, and molecules are
made of neutrons and electrons.
D. Molecules are made of atoms, and atoms are made of protons,
neutrons, and electrons.

i think slash and

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.