NJC H2 Chem 2012 Prelim P1 QP

1 NATIONAL JUNIOR COLLEGE SH2 PRELIMINARY EXAM Higher 2 CANDIDATE NAME SUBJECT CLASS REGISTRATION NUMBER CHEMISTRY 9647/01 Paper 1 Multiple Choice Fri 21 Sept 2012Additional Materials: Multiple Choice Answer Sheet 1 hourData Booklet READ THESE INSTRUCTIONS FIRST Write in soft pencil. Do not use staples, paper clips, highlighters, glue or correction fluid. Write your name, subject class and registration number on the Answer Sheet in the spaces provided unless this has been done for you. There are 40 questions on this paper. Answer all questions. For each question there are four possible answers A, B, C and D. Choose the one you consider correct and record your choice in soft pencil on the separate Answer Sheet. Read the instructions on the Answer Sheet very carefully. Each correct answer will score one mark. A mark will not be deducted for a wrong answer. Any rough working should be done in this booklet. This paper consists of 18 printed pages and 0 blank page. NJC/H2 Chem/01/2012 [Turn over

2 NJC/H2 Chem/01/2012 [Turn over Section A For each question there are four possible answers A , B, C , and D. Choose the one you consider to be correct. 1 Which atom has the highest ratio of unpaired electrons to paired electrons in its ground state? A boron B carbon C nitrogen D oxygen 2 Bombardment of 14N with a-particles (helium nuclei) produces a hydrogen nucleus and another nucleus. This other nucleus is A 14C6 B 14N7 C 17O8 D 18Ne10 3 The successive ionisation energies (kJ mol ─1) of two elements are given below: X 1012 1907 2914 4964 6274 21267 26431 29876 35905 Y 1251 2298 3822 5159 6542 9362 11108 33604 38860 Which of the following statements is false? A The formula of the compound formed between X and Y is XY 3. B The compound formed between X and Y is covalent. C X has a giant covalent structure. D Y exists as diatomic molecules. 4 When the N2+ ion is formed from N2, a σ bonding electron is removed. Which statement is correct? A The bond order decreases so N2+ has a stronger, shorter bond than N2. B The bond order decreases so N2+ has a weaker, longer bond than N2. C The bond order increases so N2+ has a stronger, shorter bond than N2. D The bond order increases so N2+ has a weaker, longer bond than N2.

3 NJC/H2 Chem/01/2012 [Turn over 5 In which pair of species are the values of the bond angles the closest? A BF3 and NH3 B CH3‒ and BF3 C H2O and C2H4 D NH4+ and SO42‒ 6 10 cm3 of hydrocarbon is burnt in 100 cm3 of excess oxygen at room temperature. The final volume of gas mixture is 85 cm 3. When the gas mixture is bubbled through aqueous sodium hydroxide solution, the volume of gas mixture decreases to 55 cm 3. What is