Chemistry Past Questions and Answers

(a)(i) State three methods of preparing salts, giving one example in each case of a salt so prepared.<br/>(ii) What type of salt is each of the following? NaH\(_2\)PO\(_4\); (CH\(_3\)COO)\(_2\)Pb; KAI(SO\(_4\))\(_2\). 12H\(_2\)O.<br/> <br/>(b)(i) Write an equation for the reaction between dilute HCI and a solution of AgNO\(_3\).<br/>(ii) Explain why NaNO\(_3\) is preferred to AgNO\(_3\) in the preparation of oxygen by thermal decomposition of trioxonitrate (V) salts.<br/>(iii) When silver wire was dipped into an aqueous solution of CuSO\(_4\), the wire remained intact but when the wire was replaced with zinc rod, the rod decreased in size. Give an explanation for this observation.<br/> <br/>(c) When a sample of a crystalline salt X was exposed to air, there was a loss in mass.<br/>(i) What phenomenon was exhibited by X?<br/>(ii) Suggest two substances which X could be.<br/>(iii) On heating 5.00 g of a fresh sample of X to constant mass, 1.80g was lost in the form of water vapour. Calculate the number of molecules of water of crystallization in one molecule of X. [H = 1.00; O = 16.00; Anhydrous form of X = 160 g mol\(^{-1}\)

The electronic configuration of an element is 1s <sup style='font-size: smaller;'>2</sup>2s<sub style='font-size: smaller;'>2</sub>2p<sub style='font-size: smaller;'>6</sub>3s <sub style='font-size: smaller;'>2</sub><br/>3p<sub style='font-size: smaller;'>3</sub>. Where is the element located in the periodic table?

Group O of elements are unreactive because

An element X with electronic configuration 1s<sub style='font-size: smaller;'>2</sub>2s<sub style='font-size: smaller;'>2</sub>2p <sub style='font-size: smaller;'>6</sub>3s <sub style='font-size: smaller;'>2</sub>3p<sub style='font-size: smaller;'>5</sub>combines with another element Y with the configuration 1s<sub style='font-size: smaller;'>[/sub]2s[sub]2</sub>2p<sub style='font-size: smaller;'>2</sub>3s<sub style='font-size: smaller;'>3</sub>3p<sub style='font-size: smaller;'>5</sub>. What is the formula of the compound formed?

Which of the following statements about dative bonding is not correct?