1. What is the name of the pigment that gives the green colour to plants? carotene chlorophyll xanthophyll phenolphthalein

2. This metal oxide is often added to paint to make it bright white. titanium dioxide iron oxide calcium oxide tin oxide

3. What is the pigment in the skin of oranges that gives it the orange colour? carotene alanine pheophytin 3-amino-4-nitrophenol

4. Henna has been used since ancient times to dye hair. But what is the compound present in henna that creates the red colour? triethylamine 1,4-diaminoanthraquinone lawsone naphthalene

5. What is the name of the pigment present in hair that gives it a dark colour? 4-methylacetophenone lactose ethylenediamine melanin

6. This dye can be obtained from the woad plant and has been used for centuries as a blue colourant. tannin vermilion saffron indigo

7. What is the name of the pigment that gives tomatoes their red colour? cyclohexene lycopene diethyl malonate pheophytin

8. The gemstones ruby and sapphire are both forms of aluminium oxide - alumina (Al2O3). Their different colours are caused by metal ion impurities replacing aluminium ions at random points throughout the structure. Which metal ion impurity is responsible for ruby's red colour? iron 3+ and titanium 4+ chromium 3+ iron 3+ copper 2+

9. This expensive spice has a beautiful yellow colour and is used not only in food, but also as a dye. paprika saffron cloves cumin

10. What is the name of the red stain obtained from cochineal insects? scarlet carmine magenta cerise