I need the correct answer for this question please​

What is the difference between electrically neutral objects and electrically charged objects

What is the thinnest soap film (excluding the case of zero thickness) that appears black when illuminated with light with a wavelength of 480 ? the index of refraction of the film is 1.34, and there is air on both sides of the film. express your answer in nanometers. hint 1. how to approach th

The doctor lands his tardis on a planet whose radius is 1.2x10^7m the acceleration due to gravity is 18m/s^2. what is the mass of the planet