Which of the following would best reflect sound waves and create an echo? a soft, flat carpet
a hard, flat piece of wood
a hard, bumpy piece of metal
a soft, bumpy curtain

The table compares the number of electrons in two unknown neutral atoms. comparison of electrons atom number of electrons a 10 d 11 use this information to determine the number of valence electrons in the atoms. which of the following correctly compares the stability of the two atoms? both are unreactive. both are highly reactive. a is unreactive and d is reactive. a is reactive and d is unreactive.