What is the proper way to write the code for rgb color format?

What name do we use for the following color format: #90a0d2?

True or false: Some colors can be referred to by written names in CSS, such as "white", "black", or "red".

In the rgba format what does the "a" represent?

In this color: rgb( 231, 56, 141 ), what does the value 56 represent?

True or false: The opacity value in the rgba format is scaled from 0 to 1.

True or false: Every possible color in CSS has a name that can be used for it.