OCR A Jun 2017 Paper 1 Q16

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SECTION B Answer all the questions. 16 This question is about ions and compounds containing hydrogen. (a) Lithium aluminium hydride, LiAl H4, contains the Al H4 Draw a dot-and-cross diagram to show the bonding in an Al H4 Show outer electrons only.ion.ion. (b) Nitrogen forms NH4 + and NH2ions. Predict the name of the shape of, and HNH bond angle in, NH4 + and NH2 . Ion NH4 NH2 Name of shape HNH bond angle[1] [2]<br /> (c) Nitrogen, phosphorus and arsenic are in Group 15 (5) of the periodic table. The boiling points of their hydrides are shown below. Element Hydride Boiling point / C N P As NH3 PH3 AsH3 33 88 55 (i) Explain why the boiling point of PH3 is lower than the boiling point of NH3.[2] (ii) Explain why the boiling point of PH3 is lower than the boiling point of AsH3.[2]<br />

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