What is the frequency of a wave? What unit is used to describe the frequency of a wave?

Choose all that apply during the years of the industrial revolution 1. the average life expectancy decreased 2. the worlds population decreased 3. birth rates decreased 4. the average like expectancy increase

The declaration of independence gave the americans concrete reasons for the revolution

Ascientist performs an experiment where she measures the mass of a piece of metal, pours acid onto the metal, washes the metal, and then re-measures the mass of the metal. the scientist repeats the experiment several times, each time increasing the amount of acid used. the dependent variable in the experiment is the: initial mass of the metal final mass of the metal amount of acid used washing the metal