Final answer:
To find the refractive index of the gas in the glass block, measure the angles of incidence and refraction for light entering the gas from the glass, and use Snell's law to solve for the index of refraction.
Step-by-step explanation:
To find the refractive index of the gas in the glass block, you will need to measure the angle of incidence and the angle of refraction for light entering the gas from the glass. Since these two angles can be measured and the index of refraction of the glass is known, you can solve for the index of refraction of the gas using Snell's law.