[barbecue123]

Hi everyone! Could someone help me with this simple exercise?

Xanthophyll contains atoms of carbon, hydrogen and oxygen in the ratio 20:28:1. Its molecules each have six oxygen atoms. Write the chemical formula of xanthophyll.

Thanks for the *delete me*

[Arkcon]

Greetings, barbecue123:, I'd like to welcome you and all the new students to the Chemical Forums.  But I'd like to as you to trouble yourself to read our Forum Rules{click}. You already accepted them when you signed up for our forum, and they apply to you, whether you agree with them or not, or even if you're unaware of them. 

We want to see your work, and then, we want to give you hints, so that you learn for yourself.   Let's get started.

You have six oxygen atoms.  You have the ratios.  Can you multiply, and show us what you have?

[barbecue123]

Pardon me, I'll show you my guess:
Having the ratio and the hint of the six oxygen atoms per molecule, I would multiply the ratio numbers by the factor 6, obtaining C₁₂₀H₁₆₈O₆

Unfortunately, when I read the solution for this problem, I saw C₄₀H₅₆O₂
So I thought I misunderstanded the request

[Borek]

in the ratio 20:28:1

Mass ratio, or atom ratio?

[barbecue123]

in the ratio 20:28:1

Mass ratio, or atom ratio?

I have reported exactly the text of the exercise. No mention of mass in there. I think it's atom ratio

[Borek]

I have reported exactly the text of the exercise. No mention of mass in there. I think it's atom ratio

Probably. Looks like a mistake in the answer key.

[jasongnome]

I have reported exactly the text of the exercise. No mention of mass in there. I think it's atom ratio

Probably. Looks like a mistake in the answer key.

I'd agree, with the question as written, the student's answer was correct and the mark scheme one wrong.

[Corribus]

Probably. Looks like a mistake in the answer key.

It's more likely a mistake in the wording of the question. Xanthophyll dyes typically have around 40 carbons, not 120. E.g., one of the xanthophyll dyes with formula C₄₀H₅₆O₂ is zeaxanthin.