Half life is the time taken by a radioactive isotope to decay by half of its original mass. In this case the half life of carbon-14 is 5500 years. The original mass is 30 g and the new mass is 3.75 g. New mass = Original mass × (1/2)^n, where n is the number of half lives; 3.75 = 30 × (1/2)^n 1/8 = (1/2)^n n = 3 Thus, the time taken will be; 3 × 5500 = 16500 years.
Moth with dark wings under the tree with dark bark have a higher chance of surviving as its wings protect them from predator due to similar colour features.
