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Q.
Which of the following materials takes the longest time for biodegradation?
Environmental Issues
Solution:
Bones are made up of proteins (mainly collagen), inorganic minerals (calcium, hydroxyapatite) and organic ground substance. Out of the four options given, bone degradation will take the longest time. Collagen, because of its unique structures in one of the most resistant proteins to degradation. Inorganic ions like $Ca^{2+}$, further strengthen the bones.