1. A rainbow is an arch of seven different colors, red, orange, yellow, green, blue, indigo and violet.
(is this grammatically correct?)
2. What is the color of the tulip?
3. What's the tulip's color?
4. It's pink.
5. It's the color pink.
6. It's the pink color.
(What about the questions and answers? Are they all correct?)
They're all correct. However, # 6 is rarely used.
1. Yes, the given sentence is grammatically correct. It properly lists the seven different colors of a rainbow.
2. The question "What is the color of the tulip?" is a grammatically correct way to ask about the color of a tulip.
3. The question "What's the tulip's color?" is also grammatically correct and conveys the same meaning as the previous question.
4. The answer "It's pink." is grammatically correct and states the color of the tulip clearly.
5. The answer "It's the color pink." is also grammatically correct. It adds emphasis to the color by specifying that it is indeed the color pink.
6. The answer "It's the pink color." is grammatically correct as well, although it might sound slightly less natural than the previous answers. Instead, it might be more common to say "It's pink in color." or simply "It's pink."