Carbon-14 is the only radioactive isotope of carbon that occurs naturally. State one similarity and one difference in the composition of the nuclei of atoms of different isotopes of the same element.

9(a)(ii)Half Life Exponential DecayMedium3 marks

When a tree dies, no new carbon-14 is absorbed by the tree. A tree contains 16

μ

g of carbon-14 when it dies. Carbon-14 has a half-life of 5700 years. On Figure 9.1, sketch a graph to show how the mass of carbon-14 in the tree decreases during the first 15 000 years after the tree dies. Show your working and label the axes with suitable values for one point on the graph.

Draw with the mouse or a finger.

9(b)Radiation Properties Uses SafetyEasy1 mark

Complete the sentence about radiation. Ionising nuclear radiation that is always present in the environment is known as ___ radiation.

9(c)Radiation Properties Uses SafetyEasy1 mark

State one source that makes a significant contribution to the ionising nuclear radiation that is always present in the environment.