What is meant by a chemical bond? why do atoms form bonds with each other? why do some element esist as molecules in nature instead of as free atoms?

What is the name of this hydrocarbon?

Which atom or ion is the largest? a. k b. k+ c. ca d. ca2+ e. li

Ammonium perchlorate nh4clo4 is the solid rocket fuel used by the u.s. space shuttle. it reacts with itself to produce nitrogen gas n2 , chlorine gas cl2 , oxygen gas o2 , water h2o , and a great deal of energy. what mass of nitrogen gas is produced by the reaction of 2.1g of ammonium perchlorate?