Potassium has an atomic number of 19. What is its electron configuration?
a. Shells 1 and 2 are full, and shell 3 has nine electrons.
b. Shells 1,2,
and 3 are full, and shell 4 has three electrons.
c. Shells 1,2,
and 3 are full, and shell 4 has one
d. Shells 1,2,
and 3 are full, and no other electrons are present.

The combustion of methane, ch4, releases 890.4kj/mol. that is, when one mole of methane is burned,890.4 kj are given off to the surroundings. this meansthat the products have 890.4 kj less than the reactants.thus, ah for the reaction = - 890.4 kj. a negative symbolforah indicates an exothermic reaction.ch (g) + 20 (g)> co2 (g) + 2 h0 (1); ah = - 890.4 kga) how much energy is given off when 2.00 mol of ch,are burned? b) how much energy is released when 22.4g of ch. areburned?