What is the internal energy of a system? what is the variable for internal energy?

Explanation:

Internal energy is the sum of all the energies inside or within a system because molecules of the system will have kinetic, potential, rotational, vibrational etc energies.

Internal energy arises because of random or disordered movement of particles within a system.

Therefore, internal energy of a system is the sum of kinetic and potential energy of all the particles present inside the system.

The variable for internal energy is "U". Also, change in internal energy is represented by .

explanation:

i think option no d is the correct answer

alkaline metals are lithium, sodium, rubidium, potassium, cesium and francium.

alkali metals have electronegativity from 0.7 to 1, lowest in periodic table of elements, which means that alkali metals (i group in periodic table) has positive oxidation number in compounds.

electronegativity is a chemical property that describes the tendency of an atom to attract a shared pair of electrons towards itself.

alkaline metals (far left in main group) have lowest ionizations energy and easy remove valence electrons,

for example, potassium is the alkali metal and has a single valence electron in the outer electron shell.

electron configuration of potassium is: ₁₉k 1s²2s²2p⁶3s²3p⁶4s¹.

they can not exist alone in nature, because they are very reactive.