I believe it is. It is a copyrighted product with a world market. It is named and marketed as Rice Krispies (R).
I don't know about a proper adjetive, but I know how to turn a proper noun into a proper adjective. A proper noun is the proper name of a country, organization, corporation such as Great Britain, America, Spain. Proper adjectives modify nouns as in British flag, American schools, Spanish rice. There, proper nouns (Britain, America, Spain) have been turned into proper adjectives. How about the Universe into universal? Queen Elizabeth from the Elizabethan period? Does this help?Very briefly, when you use a proper noun, for example, Kennedy, to describe another noun, as in Kennedy Administration, grammatically speaking, you are using that proper noun as a proper adjective. It's that simple.
Switzerland is the proper noun.
proper noun
Is jer a proper noun
proper
Rice Krispies was created in 1928.
I eat rice krispies all the time and I have not, or have never heard a word about getting cancer from rice krispies.
Rice Krispies Treats are made by Kelloggs
65
"What do your Rice Krispies say to you?"
The total number of calories in Rice Krispies is 120.
No, "rice" is a common noun, as it refers to a type of grain that is widely cultivated and consumed.
Cocoa Krispies
Rice Krispies Treats
Rice Krispies, Chocolate, Marshmallow
Rice Krispies
they are rice krispies but they make the brown from mushing up bits of rabbit poo and spitting it on the rice krispies