You are trying to pass a dataframe to a function that is requesting a numeric vector:
> is.numeric(iris[,-5])
[1] FALSE
> str(iris[,-5])
‘data.frame’: 150 obs. of 4 variables:
$ Sepal.Length: num -0.898 -1.139 -1.381 -1.501 -1.018 …
$ Sepal.Width : num 1.0156 -0.1315 0.3273 0.0979 1.245 …
$ Petal.Length: num -1.34 -1.34 -1.39 -1.28 -1.34 …
$ Petal.Width : num -1.31 -1.31 -1.31 -1.31 -1.31 …
Try passing just a single column, like:
pnorm(iris[,1])