2019 VJC H2 Chem Prelim P1 QP and Ans

2 VJC PRELIM 9729/01/19 2019 VJC H2 Chem Prelim P1 For each question there are four possible answers, A, B, C, and D. Choose the one you consider to be correct. 1 Use of the Data Booklet is relevant to this question. Which of the following statements are incorrect? 1 Both isotopes of Ti22 56 and Ti22 58 have more neutrons than electrons. 2 The first ionisation energy increases continuously from sodium to phosphorus as the number of protons increases but number of inner quantum shells remains the same. 3 The second ionisation energy of chromium is lower than the second ionisation energy of manganese as manganese has one more proton than chromium. A 1, 2 and 3 C 2 only B 2 and 3 only D 3 only 2 In which of the following pairs does the first substance have a higher melting point than the second substance? first substance second substance A CH3CH2OCH3 CH3CH2NHCH3 B CH3CH2CH2CH2OH CH3CHClCH2CH2OH C RbCl KCl D H2NCH2COCO2H H2NCH2CH2CO2H

3 VJC PRELIM 9729/01/19 [Turn Over 3 The dye ‘alizarin’ sticks fast to cotton when a ‘mordant’ containing aluminium ion is used. Under alkaline conditions, the aluminium ions become bonded to the hydroxyl groups of cotton. The dye ‘alizarin’ can then bond with the aluminium ions, giving the structure below which dyes cotton red. OO O OH Al3+ O OHH Which statement is correct? A The formula for ‘alizarin’ ion is C14H9O4–. B There are 12 carbon atoms in the ‘alizarin’ ion that are sp2 hybridised. C In the absence of a mordant, alizarin can bind to cotton via hydrogen bonding. D There is a decrease in the bond angles about the oxygen atoms of the cotton hydroxyl groups upon binding to aluminium ions. 4 Two vessels W and X are connected by a closed valve. Vessel X contains three times the volume of W. W contains argon gas at 20 C at a pressure of 1.00 × 105 Pa while X has been evacuated. In an experiment, the valve is opened and the temperature of the whole system is raised to T oC. The final pressure in the system decreases by 6.82 x 104 Pa. What is the final temperature in the system? A 99.7 oC C 526 oC B 373 oC D 799 oC ‘alizarin’ ion W X

4 VJC PRELIM 9729/01/19 5 The graph below shows the variation in the s tandard enthalpy change of vapo risation, ΔHovap, for eight consecutive elements in the Periodic Table, all with atomic number, 10 Z 20. Which one of the following statements is incorrect? A Effervescence of hydrogen gas is observed when sodium is added to the solution containing chloride of element P. B Element U is the most electronegative element among all the eig