International system of measurement for length, volume, mass, temperature, area, and density?

Achlorine atom has 17 protons and 18 neutrons. what is its mass number? what is its atomic number?

Calculate the first and second velocities of the car with four washers attached to the pulley, using the formulas v1 = 0.25 m / t1 , and v2 = 0.25 m / (t2 – t1) where t1 and t2 are the average times the car took to reach the 0.25 and the 0.50 meter marks. record these velocities, to two decimal places, in table e.

Me with this and you will be marked brainliest