What is the change in entropy of helium gas with total mass 0.135 kg at the normal boiling point of helium when it all condenses isothermally to liquid helium? Assume that the normal boiling point of helium is 4.216 K and the heat of vaporization of helium is 2.09×104 J/kg .

-669.2 J/k

Explanation:

We are given that

Mass=m=0.135 kg

Normal boiling point,B.P=4.216 K

Heat f of vaporization=

We have to find the change in entropy of helium gas.

Using the formula then, we get

Hence, the change in entropy of helium gas=-669.2 J/k

you'd use the equation that establishes a relationship between  energy  and  wavelength, which looks like this

e=h⋅cλ, where

λ  - the wavelength of the photon; c  - the speed of light, usually given as  3⋅108m/s; h  -  planck's constant, equal to  6.626⋅10−34j s

plug the value you were given for the energy of the photon in the above equation to get the wavelength

e=h⋅cλ⇒λ=h⋅ce

λ=6.626⋅10−34js⋅3⋅108ms−1.257⋅10−24j=1.581⋅10−1m