Which statement correctly describes an atom of the element helium? a. an atom of helium has eight electrons in its outer energy b. an atom of helium most similarly behaves like an atom of hydrogen since it is in the same period. c. an atom of helium has a full outer energy level and is therefore unusually reactive. d. an atom of helium has its valence electrons in its first energy level.

Option c

Explanation:

Atomic number of helium is 2.

Electronic configuration of He =

First energy shell of an atom is known as K shell. It has only one sub shell 's sub shell'.

K shell or energy level can accommodate maximum of 2 electrons. Helium has 2 electrons and these two electrons are filled in K shell. So, atom of helium has a full energy level.

Elements having full energy level or eight electrons in their valence shell is stable and therefore chemically inactive or inert.

As outer shell of helium is full, so it is chemically inactive.

o conteúdo de calor de um sistema é igual à entalpia apenas para um sistema que é constante