In which ways do humans affect the environments of animals?

The enthalpy of formation of water is -285.8 kj/mol. what can be inferred from this statement?

1) these are barrel shaped microtubules in most animal cells, that organize the spindles during cell division

Zoe is investigating the composition of substance a, an unknown substance. using chemical processes, she analyzes substance a and determines it is composed of sodium, oxygen, and hydrogen atoms in a ratio of 1 : 1 : 1. what is substance a? a. a compound b. an element c. a heterogeneous mixture d. a homogeneous mixture