Set 3 Chemistry [Paper] 1

Read like a detective quote by Acholiboy Js Felix Rubangakene Jr Geofrey 1 SECTION A -46 MARKS Attempt all questions in this section. 1. Beryllium, magnesium & calcium are group II elements. a. Write the general outer configuratio n of the elements. (01 mark) ……………………………………………………………………………………………………… b. Each of these elements reacts with carbon to form carbides. Write the equation for the reaction which occurs when each carbide reacts with water. (03 marks) ………………………………………………………… …………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………. 2. a. Define nuclear stability. (01 mar k) ………………………………………………………………………………………………………… ………………………………………………………………………………………………………… ………………………………………………………………………………………………………… ………………………………………………………………………………………………………… b (i). The graph below shows the variation of numbers of neutrons in an atom with proton numbers. n/p = 1 20 83 No of protons Number of neutrons Explain why the bend of nuclear stability deviates from 𝑛 𝑝 = 1 after atomic number 20. (02 marks) Read like a detective quote by Acholiboy Js Felix Rubangakene Jr Geofrey 2 ……………………… ………………………………………………………………………………… ………………………………………………………………………………………………………… ………………………………………………………………………………………………………… ………………………………………………………………………………………………………… ………………………………………………………………………………………………………… ………………………………………………………………………………………………………… (ii).Given that the respective mass numbers and atomic numbers of thorium and lead are 232 and 90,208 and 82. Determine the number of alpha and beta particles that must be emitted by thorium to transform to lead. (02 marks) ………………………………………………………………………………………………………… ………………………………………………………………………………………………………… ………………………………………………………………………………………………………… ………………………………………………………………………………………………………… ………………………………………………………………………………………………………… …………………………………………………………………………………………………………. 3. 50.0cm3 of 0.1M aqueous ammonia was added to 50.0cm3 of 0.1 M hydrochloric acid and the resultant solution had a pH less than 7. a. Give a reason for this observation. (02 marks) ………………………………………………………………………………………………………… ………………………………………………………………………………………………………… ………………………………………………………………………………………………………… ………………………………………………………………………………………………………… ……………………………………………………………………………………………………….. b. Calculate the pH of the solution . (Kh for the ammoni um chloride is 6.34 X 10-8mol/dm3) (03 marks) ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………. Read like a detective quote by Acholiboy Js Felix Rubangakene Jr Geofrey 3 4. State what would be observed and write equation between the following compounds and the reagent commonly used in identifying …