Cobalt has a mass number of 59 and an atomic number of 27. A student wants to create a model of a cobalt atom. Which statement about the model is correct

chemical properties are the characteristic of matter which can only be observed by changing the chemical identity of a sample like flammability reactivity and toxicity.

the reaction mixture contains some ammonia, plus a lot of unreacted nitrogen and hydrogen. the mixture is cooled and compressed, causing the ammonia gas to condense into a liquid. the liquefied ammonia is separated and removed. the unreacted nitrogen and hydrogen are then recycled back into the reactor .