Is it possible for a float type variable to be placed in an area of memory set up as double when using the scanf() function?

My line of thinking was that a float is 4 bytes and a double is 8 bytes, so this conversion should be ok, it’s like 1/2 a litre into 1 litre right?

I am confused over a question posed to me that states that this conversion is not possible; maybe I do not understand the question properly. The question is:

"When utilising the scanf() function, why is it not possible for a float type variable to be placed in an area of memory set up as double?"

Thanks,