Which is the main difference between protons and neutrons

What are the two major rules associated with polarity

Which best describes the present-day universe? opaque, expanding very slowly, stars produce heavy elements transparent, expanding at an accelerated rate, stars produce heavy elements opaque, expanding at an accelerated rate, stars produce only hydrogen and helium transparent, expanding very slowly, stars produce only hydrogen and helium

Calculate the temperature rise when 0.2g of propane is used to heat 400cm cubed of water.