NJC Prelim P2_QP

1 NJC SH2 Preliminary Examination 9729 / 02 / 18 [Turn Over NATIONAL JUNIOR COLLEGE SH 2 PRELIMINARY EXAMINATION Higher 2 CANDIDATE NAME SUBJECT CLASS REGISTRATION NUMBER CHEMISTRY Paper 2 Structured Questions Candidates answer all questions on the Question Paper. Additional Materials: Data Booklet 9729/02 Tues 21 Aug 2018 2 hours READ THESE INSTRUCTIONS FIRST Write your subject class, registration number and name on all the work you hand in. Write in dark blue or black pen. You may use a soft pencil for any diagrams, graphs. Do not use staples, paper clips, glue or correction fluid/tape. The use of an approved scientific calculator is expected, where appropriate. A Data Booklet is provided. 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. For Examiner’s Use 1 /8 2 /14 3 /13 4 /11 5 /14 6 /15 Penalty units Penalty sf Paper 2 /75 Answer ALL questions on the space provided. This paper consists of 18 printed pages.

2 NJC SH2 Preliminary Examination 9729 / 02 / 18 [Turn Over

3 NJC SH2 Preliminary Examination 9729 / 02 / 18 [Turn Over 1 The properties of elements and their compounds show similarities, differences and trends depending on the positions of the elements. (a) The elements in the third period, and their compounds, show trends in their physical and chemical properties. A sketch graph of the first ionisation energies of five successive elements in the third period is shown. (i) Sketch on the graph, the position of the ionisation energy of the two elements that come before Mg in this sequence. [1] (ii) Explain, with reference to electronic arrangements, the decreases in first ionisation energy between Mg and Al and between P and S. Mg and Al: ……………………………………………… …………………………...… …………………………………………………………………………………………… …………………………………………………………………………………………… P and S: …………………………………………………………………………….….. …………………………………………………………………………………………… …………………………………………………………………………………………… [2]

4 NJC SH2 Preliminary Examination 9729 / 02 / 18 [Turn Over (b) The chlorides of the elements in the third period behave in different ways when added to water, depending on their structure and bonding. L is a chloride of an element in Period 3. A students investigated L and the results are as given below. • L is a white crystalline solid with a melting point of 987 K. • L