What were the most significant findings in each study?

What is the momentum of a 2 kg object moving at 15 meters per second

What are atoms of the same element with varying number of neutrons

Light from a sodium lamp passes through a diffraction grating that has 1000 slits per millimeter. the interference pattern is viewed on a screen 1.000 m behind the grating. the first (m = 1) two bright yellow fringes that are visible are 0.7288 m and 0.7300 m from the central maximum. what are the wavelengths of these two fringes?