The density of air at conditions P = 1 atm and T = 20.0 °C , is 1.28 kg/m3. At what pressure is the density 0.64 kg/m3 if the temperature and number of molecules are kept constant? Answer in units of atm. PLEASE!!

Hydrogen and helium are both members of?

What is the temperature in degrees celsius of a substance with a tempature of 49k

If the radius of curvature of the cornea is 0.75 cm when the eye is focusing on an object 36.0 cm from the cornea vertex and the indexes of refraction are as described before, what is the distance from the cornea vertex to the retina? express your answer to two significant