The speed of light in a certain substance is 83% of its value in water. what is the index of refraction of this substance?

The “death throes” of stars are amongst the most complex phenomena in all of astronomy, and the “corpses” of stars amongst the most energetic and exotic objects in existence. beginning at the end of the core helium fusion stage in a star’s life, describe in detail the post-main sequence development of both (a) a 1.0 solar mass star, and (b) a 25.0 solar mass star. in what significant ways do they differ? what role does each of these types of stars play in the "star-gas-star" cycle and the evolution of chemical elements in our galaxy?

Aplane travels 1000 miles in 5 hours .what is the planes average speed?

Acertain radio station broadcasts radio waves that have a wavelength of 298cm what is its broadcast frequency?