Step-by-step explanation:
An object can only be seen when light falls on it, reflects and enters into observer's eye. We know that the white light is made up of seven colors represented as an acronym: VIBGYOR. This means when light falls on an object all the seven colors are falling on it. But every object has it own properties and it reflects some color and absorbs some colors. The color/colors which are reflected from the object will become the color of that object.
Not here the flower appear purple which means only purple light is being reflected from the flower. But if you notice there is no purple in the white light!
This happens because red and blue light is reflected off the flower which mixes and show the purple color.