NYGH 2022-S3EOY-IP Chem P1 and P2 Ans

Secondary 3 (IP) EOY Answers 2022 Sec 3 End-of-Year Exam Chemistry Answers Paper 1 1 B 2 B 3 B 4 A 5 C 6 B 7 D 8 B 9 C 10 C 11 A 12 A 13 B 14 D 15 C 16 B 17 D 18 C 19 B 20 C 21 D 22 D 23 D 24 C 25 A 26 C 27 B 28 D 29 B 30 C Qn Ans Explanation 1 B A: False, state 1 is changed to state 2 by boiling, not melting. B: True C: False, state 2 is gaseous state, so particles are moving randomly at high speed. D: False, state 3 is solid state. 2 B Mr of NH3 (17.0) is lower than that of CO2 (44.0), so NH3 will diffuse faster than CO2 and reach moist blue litmus paper first. NH3 will have no effect on moist blue litmus paper. When CO2 reaches the moist blue litmus paper, it will turn moist blue litmus paper red. Overall observation: Moist blue litmus paper turn red. 3 B Impurities increase boiling point and decrease melting point. 4 A Carbon dioxide is formed from the reaction between hydrochloric acid and calcium carbonate. Since carbon dioxide is acidic, an acidic or neutral drying agent should be used to dry the gas  from the options only concentrated sulfuric acid is suitable. Since carbon dioxide (Mr of 44.0) is more dense than air (average Mr of approximately 28.8), downward delivery should be used. 5 C Step 1: Sublimation is done to remove ammonium chloride. Note that sublimation cannot be done after the substance is dissolved in water. Step 2: Water is added to dissolve copper(II) chloride. Silver chloride remains insoluble. Step 3: Filtration is done to remove insoluble silver chloride. Step 4: Hydrated copper(II) chloride is obtained by crystallisation. 6 B 1: False, eg N2 is a molecule and an element 2. False, eg N2 is a molecule and an element 3: True, generally metals and non-metals react to form ionic compounds 7 D Proton number for Y = 79 + 2 = 81 Nucleon number for Y = 197 + 2 + 1 = 200 (add both protons and neutrons) Since 2 protons are added while only 1 electron is added, Y will have a positive charge.

From the above, answer will be option D. 8 B P: H Q: Group 1 element (Li) R: Group 16 element (O) S: Group 18 element (Ne) A: Form ionic compound, LiH with high melting point B: Form simple covalent compound, H2O with low melting point C: Form ionic compound, Li2O with high melting point D: Option can be eliminated since S is a noble gas that is inert and will not form compounds. 9 C Since total abundance must add up to 100%, x + 0.5x + (x – 0.2) = 1 x = 0.48 20(0.48) + 21(0.24) + 22(0.28) = 20.8 10 C From the structure of N2H4, there are 2 valence electrons not involved in covalent bonding for each N atom. There are 2 more inner shell electrons in each N atoms that are not involved in covalent bonding. Therefore there are 8 valence electrons not involved in covalent bonding in the molecule. 11 A Sulfur dioxide is used as a bleaching agent while sulfuric acid is used for the other stated purposes. 12 A For the titration of a weak aci