Which is the correct formula for finding the frequency of an electromagnetic wave?

There is no graph to look at on here, but i shall explain them to you. a line graph is just in its title it’s a graph with a line running through the dots to show an increase or decrease. a bar graph is used to show how much or how little something is so a comparison. a scatter plot is used to graph points to tell the data. and i don’t know what a histogram is.

The fertilized egg  begins to develop into a hollow ball of cells called the blastocyst. 

Chromium  +  hydrogen sulfate  =  chromium(iii) sulfate  +  hydrogenso then it will be  a. cr + h2so4? cr2(so4)3 + h2 

The answer is mean don't know