Exam (elaborations) Chemistry Assessment2120

1. What is thin-layer chromatography best used for separating? A. molecules of varying polarity B. molecules of similar polarity C. metals in an alloy D. water of crystallization from hydrated salts 2. Ice containing only the isotope 2 H sinks and does not melt when dropped into ordinary distilled water maintained at 3 C. Which statement is correct? A. The isotope 2 H has a high natural abundance. B. 2 H2O(s) has a higher melting point than normal ice. C. 2 H2O(s) has a lower density than normal ice-cold water. D. 2 H2O has different chemical properties from normal water. 3. The table lists successive ionization energies of an element Z. Ionization number 1st 2nd 3rd 4th 5th 6th Ionization energy / kJmol−1 577.54 1816.68 2744.78 11577.5 14841.9 18379.0 Which is the formula of the stable oxide of the element Z? A. Z2O B. ZO C. Z2O3 D. ZO2