2022 TMJC H2 Chem Prelim P2 (QP)

2022 H2 Chem Prelim P2 (QP) Answer all questions in the space provided. 1 (a) The elements of Period 3 form different oxides when reacted with oxygen. (i) State and explain the variation in bonding within the oxides across Period 3. ……………………………………………………………………………………………………... ……………………………………………………………………………………………………... ……………………………………………………………………………………………………... ……………………………………………………………………………………………………... ………………………………………………………………………………………………..... [2] Compounds A and B are oxides of Period 3 elements which exist in the solid state at room temperature. When excess water is added to a sample of A, the solid dissolve s completely and an acidic solution is obtained. However, when excess water is added to B, the solid remains insoluble and a neutral solution is obtained. (ii) Identify compound A. ………………………………………………………………………………………………….. [1] (iii) Suggest two possible identities of compound B and d escribe how the identity of compound B can be confirmed using the acid-base behaviour of Period 3 oxides. Include all relevant observations and an equation in your answer. …………………………………………………………………………………………………...... …………………………………………………………………………………………………...... …………………………………………………………………………………………………...... ……………………………………………………………………………………………….......... …………………………………………………………………………………………………...... ……………………………………………………………………………………………….......... …………………………………………………………………………………………………...... ………………………………………………………………………………………………….. [3]

2 2022 H2 Chem Prelim P2 (QP) Tampines Meridian Junior College 2022 JC2 Preliminary Examination H2 Chemistry × Na2O MgO Al2O3 SiO2 P4O10 SO3 (b) (i) Complete the variation in the melting points of Period 3 oxides. [1] (ii) Explain the variation in melting points from Na2O to Al2O3. ……………………………………………………………………………………………………... ……………………………………………………………………………………………………... ……………………………………………………………………………………………………... ……………………………………………………………………………………………………... ………………………………………………………………………………………………..... [2] melting point / °C × ×

3 [Turn over Tampines Meridian Junior College 2022 JC2 Preliminary Examination H2 Chemistry (c) Sodium azide, NaN3, is commonly used in car airbags to produce nitrogen gas upon collisions. (i) Draw a ‘dot -and-cross’ diagram for the azide ion , N3 – , showing all of the outer shell electrons. [1] (ii) State and explain, with reference to the Valence Shell Electron Pair Repulsion theory, the shape and bond angle around the central atom of N3 – . …………………………………………………………………………………………………....... …………………………………………………………………………………………………....... ……………………………………………………………………………………………….......... ………………………………………………………………………………………………….. [2]

4 2022 H2 Chem Prelim P2 (QP) Tampines Meridian Junior College 2022 JC2 Preliminary Examination H2 Chemistry When a car is involved in a collision, sensors send an electric signal to the