Which of the following describes the element kr? choose all that apply. (a) belongs to a group consisting entirely of gases forms a basic solution in water. (b) is very reactive as a metal. (c) is one of the group of the least reactive elements. (d) reacts vigorously with alkali metals to form salts. (e) consists of diatomic molecules in elemental form.

All of the following are part of the biosphere except

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?

Chris is about to do an experiment to measure the density of water at several temperatures. his teacher has him prepare and sign a safety contract before beginning the experiment. which term is mostlikely part of the safety contract