A dicot has 5 petals
none
There are indefinite number of petals in rose flower due to conversion of stamens in to petals
the gumamela or hibiscus has 5 petals in the case of a "normal" plant. there are some double cultivars which have many more
Generally five
oak
There are many plants in which sepals and petals are simlar for example is Chenopodium album (Goose feet Plant).
The amount of petals each flower cluster has on a hydrangea varies from plant to plant. The hydrangea is native to southern and eastern Asia and North and South America.
flower
This is a monocot because they have multiples of three in their petals, but the particular plant may be more than one plant.
petals
In most plants, this would be the flower; specifically, the petals.