Does anybody know what number 2 is?

An air bubble of volume 20 cm³ is at the bottom of a lake 40 m deep, where the temperature is 4.0°c. the bubble rises to the surface, which is at a temperature of 20°c.take the temperature of the bubble’s air to be the same as that of the surrounding water. just as the bubble reaches the surface, what is its volume?

An initially unpolarized light if intensity 500 w/m^2 passes through four polarizers. the transmission axis between adjacent polarizers is 45∘. what percentage of the initial intensity is transmitted by the system?

What is the energy of a photon of ultraviolet radiation with a frequency of 4.4 × 1015 hz? planck’s constant is 6.63 × 10–34