EDEXCEL A LEVEL 2023 CHEMISTRY Questions & Correct Answers/ Graded A+

State what is meant by the term d‐block element. (1) : • an element which has its last electron added to a d-subshell 2 Chemists often use the term 'orbital' when considering atomic structure. (a) State what is meant by the term orbital. (2) : a region / space (in an atom) in which there is a high probability of finding electron(s) / electron(s) are (most) likely to be found • containing (a maximum of ) 2 / a pair of electrons (with opposite spin) (1) This question is about compounds containing elements from Group 7. (a) Which change occurs when concentrated sulfuric acid is added to potassium bromide? A bromide ions oxidise sulfuric acid forming sulfur B bromide ions oxidise sulfuric acid forming sulfur dioxide 2 C bromide ions reduce sulfuric acid forming sulfur D bromide ions reduce sulfuric acid forming sulfur dioxide : D Chemists can test for the presence of bromide ions in solution by adding a small amount of acidified silver nitrate solution. The solubility of the precipitate in aqueous ammonia is then tested. (i) Which statement is correct for bromide ions? A a white precipitate forms that dissolves in concentrated ammonia only B a white precipitate forms that dissolves in both dilute and concentrated ammonia C a cream precipitate forms that dissolves in concentrated ammonia only D a cream precipitate forms that dissolves in both dilute and concentrated ammonia : C (ii) Give a reason why the silver nitrate must be acidified. 1 : To remove the carbonate ion