4.Calculate the Hydroxide, Hydrogen ion and POH of solution if the PH of solution is 7.b 5.Solution A Has PH =4 and solution B has PH = 7.How many times greater is the Hydroxide ion
concentration in solution A than the Hydronium ion concentration in solution B

the ph is gonna be your value and the 4 is gonna be your main subject

so as the ph is your value u gonna ad your ph and 7 and 4 toghter then multiple your answer 2 times  because ph represent multiple and your value  

the ozone layer acts as a filter for the shorter wavelength and highly hazardous ultraviolet radiation (uvr) from the sun, protecting life on earth from its potentially harmful effects. when the sky is clear, there is an inverse relationship between stratospheric ozone and solar uvr measured at the earth's surface.