What is the function of this instrument?

What are transitions between a liquid and gas called? identify which way they are transitioning

Covalent bonds generally form when the bonded elements have a difference in electronegativity less than 1.5. subtract the electronegativities for the following pairs of elements and predict whether they form a covalent bond. electronegativity difference of c and c: ionic covalent electronegativity difference of mg and cl: ionic covalent

Quickly what are the following of organisms that existed over a wide area but only for a limited time period called a. soft fossils b. mold fossils c. index fossils d. trace fossils