What organelle of skeletal muscle cells stores calcium used in muscle contaction?

The energy required to vaporize a certain amount of a substance is greater than the amount of energy necessary to raise the temperature of the same amout of that substance by 1 degreee celcius

What best explains whether bromine (br) or neon (ne) is more likely to form a covalent bond? bromine forms covalent bonds because it has seven valence electrons, but neon has eight valence electrons and already fulfills the octet rule. bromine forms covalent bonds because it has many electron shells, but neon has only two electron shells and is tightly bound to its electrons. neon forms covalent bonds because it can share its valence electrons, but bromine has seven valence electrons and can gain only one more electron. neon forms covalent bonds because it has only two electron shells, but bromine has many electron shells and will lose electrons in order to fulfill the octet rule.

Several billion years ago which gas was the least prevailant in the atmosphere