2013_TPJC_H1_Chemistry_P2 QP

TPJC_2013_8872_02 [Turn over TAMPINES JUNIOR COLLEGE JC2 Preliminary Examination CANDIDATE NAME TUTOR NAME 1 2 CHEMISTRY Paper 2 Candidates answer Section A on the Question Paper. Additional Materials: Answer Paper Data Booklet 8872/02 Thursday, 05 September 2013 2 hours H1 CIVICS GROUP For Examiner’s Use Section A B5 B6 B7 Total READ THESE INSTRUCTIONS FIRST Write your name and civics group on all the work you hand in. Write in dark blue or black pen. You may use a pencil for any diagrams, graphs or rough working. Do not use staples, paper clips, highlighters, glue or correction fluid. Section A Answer all the questions. Section B Answer two questions on separate answer paper. At the end of the examination, fasten all your work securely together. The number of marks is given in brackets [ ] at the end of each question or part question. This document consists of 14 printed pages.

2 TPJC_2013_8872_02 Section A Answer all questions in this section in the spaces provided. For Examiner’s Use 1 Radiotherapy is the medical use of radiation generated from radioactive isotopes to destroy or weaken malfunctioning cells. Examples of radioactive isotopes used for the therapy are those of iodine, phosphorus and lutetium. (a) Lutetium has two naturally occurring isotopes, 175Lu and 176Lu. Their natural abundances are 97.4% and 2.6% respectively. (i) Define the term relative atomic mass. …………...…………..………………………………………………………….…… …………...…………..………………………………………………………….…… …………...…………..………………………………………………………….…… (ii) Calculate, to one decimal place, the relative atomic mass of lutetium. [2] (b) 176Lu has a half-life of 101078.3 × years. The half-life of a radioactive isotope is the time taken for half of the atoms in a given mass to decay. Calculate the percentage of a sample of 176Lu isotopes remaining after 1110134.1 × years. [2] Iodine-131 is used to treat the thyroid for cancers and phosphorus-32 is used to control the excess of red blood cells produced in the bone marrow. (c) Complete the table below for the 131I and 32P isotopes. Isotope Number of protons Number of neutrons 131I 32P [1]

3 TPJC_2013_8872_02 [Turn over Radioactive isotopes are commonly incorporated into compounds to trace the path of biochemical reactions. These compounds are known as radioactive tracers. The structure of fluorodeoxyglucose (18F-FDG), a radioactive tracer widely used in medical imaging, is shown below. O OH OH F18 OH OH For Examiner’s Use 18F-FDG (d) (i) Apart from ether (–O–), circle and name the functional groups that are present in the 18F-FDG shown above. (ii) Calculate the percentage composition by mass of carbon in 18F-FDG. (iii) Would you expect 18F-FDG to be