Choose the electron configurations which are possible for an unexcited atom. Example 1 – 1s22s22p4 Example 2 – 1s22s22p63s23p33d1 Example 3 – 1s22s22p83s1 Example 4 – 1s22s22p63s1

Examples 1, 3 and 4

Explanation:

An unexcited atom is an atom in the ground state i.e the atom has it's valence electrons in it's lowest energy level possible. This actually implies the normal electronic configuration of the atom. Thus, examples 1, 3 and 4 have the actual electronic configuration with there valence electrons in the lowest possible energy level.

Example 1: 1S² 2S² 2P⁴

Example 3: 1S² 2S² 2P⁶ 3S¹ (There seem to be a mistake in the question provided, P energy level can only 6 electrons not 8)

Example 4: 1S² 2S² 2P⁶ 3S¹

NOTE: If you take a look at example 2, it will be deduced that the 3P energy level has only 3 valence electrons and the last valence electron jumped to 3d energy level; making that atom appear to be in it's excited state.

a rain shadow is a dry region of land on the side that is protected against the prevailing winds of a mountain range. the prevailing winds are the winds that occur most of the time in a particular place of the earth

prevailing winds carry air toward the mountain range. as the air rises up over a mountain range, the air cools, water vapor condenses, and clouds form. on this side of the mountains, called the windward side, precipitation falls in the form of  rain  or snow. this dry air produces a  rain shadow.

answer:

the answer is 6 valence electrons.

explanation:

valence is the # of electrons on the outer most shell of an atom.

oxygen has 6.

although, the valency of oxygen is 2, because it only needs to make 2 covalent bonds, or gain 2 electrons, to achieve the stable octet configuration of a noble gas.

that's it!

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