The atomic number of an element is 12. based on its electron arrangement, which of the following explains its correct position in the periodic table?
a)group 3, because it has two electrons in the 3p orbital.
b)group 2, because it has two electrons in the 3p orbital.
c)group 3, because its last electron is in the 3p orbital.
d)group 2, because its last electron is in the 2p orbital.

Group 2, because it has two electrons in the 3s orbital.

Explanation:

Electronic configuration represents the total number of electrons that a neutral element contains.Thus for element with atomic number 12 contains 12 electrons.

The electrons are filled according to Afbau's rule in order of increasing energies and thus the electronic configuration is :

As the element belongs to s-block, as last electron enters s orbital,  its group number = Number of valence electrons (or outermost shell electrons), which is 2.

Thus group number is 2.

that's what i got you can count the number of atoms

water at room temperature is flowing through a pipe with pressure taps located 10 ft apart along one section of the pipe, which are connected to a mercury (s=13.6) manometer.