You need to know the energy frequency relationship for photons, which is thanks to Max Planck:
Photon Energy = Planck constant x Frequency
Rarranged:
Photon Energy / Planck Constant = Frequency
Planck Constant = 6.63x10^-34
2.93x10^-25 / 6.63x10^-34 = Frequency
A physical change is when something don't permanently change
An acid, acids have a pH less than 7
A physical property is an aspect of matter that can be observed or measured without changing it. A chemical property may only be observed by changing the chemical identity of a substance.
First convert volume to mass:
mass = 0.789 g/mL * 155 mL = 122.295 g
Then convert mass to number of moles:
number of moles = 122.295 g * (1 mole / 46 g) = 2.66 moles
Using avogadros number, we get the molecules:
<span>number of molecules = 2.66 moles * 6.022 x 10^23 molecules
/ mole = 1.6 x 10^24 molecules</span>
