One of the signs of a chemical reaction is taking place

In a ball-and-stick molecular model, what do the sticks represent?

Bridget is in science class. her teacher gives her two unknown substances and asks her to determine their relative ph. she places a piece of red litmus paper into both substances. the litmus paper turns purple when she places it into substance i. the litmus paper turns blue when she places it into substance ii. a. substance i is a neutral substance and substance ii is an acid. b. substance i is a neutral substance and substance ii is a base. c. substance i is an acid and substance ii is a base. d. substance i is a base and substance ii is a neutral substance.

An element x has two isotopes. x–15 has 7 protons and 8 neutrons. determine the atomic number and mass number of the second isotope, which has 10 neutrons in its nucleus.