Waec Chemistry Questions
Question 241:
(a) Three elements A, B and C have atomic numbers 8, 11 and 12 respectively.
(i) Write the formula of the compound formed by the chemical combination of A and B.
(ii) State which of the three elements belong(s) to the s-block of the Periodic Table. Give reason for your answer:
(b) List the component elements of bleaching powder.
View Answer & Explanation(i) Write the formula of the compound formed by the chemical combination of A and B.
(ii) State which of the three elements belong(s) to the s-block of the Periodic Table. Give reason for your answer:
(b) List the component elements of bleaching powder.
Question 242:
(a) Name one metal in each case Which:
(i) exists as a liquid at room temperature,
(ii) can be found in nature in the uncombined state
(b) X and Y are 0.5 mol. dm\(^{-3}\) freshly prepared aqueous solutions of two salts of iron
(II) With excess sodium hydroxide solution, X gave a dirty green precipitate which was not obtained in the case of Y.
View Answer & Explanation(i) exists as a liquid at room temperature,
(ii) can be found in nature in the uncombined state
(b) X and Y are 0.5 mol. dm\(^{-3}\) freshly prepared aqueous solutions of two salts of iron
(II) With excess sodium hydroxide solution, X gave a dirty green precipitate which was not obtained in the case of Y.
Question 243:
(a) What is meant by the term acid salt? Give one example.
(b) State the reason why an all-glass apparatus must be used for the laboratory preparation of concentrated trioxonitrate (V) acid.
View Answer & Explanation(b) State the reason why an all-glass apparatus must be used for the laboratory preparation of concentrated trioxonitrate (V) acid.
Question 244:
(a) Name: (i) one structural isomer of glucose.
(ii) the process by which starch is converted to glucose.
(b) The open-chain structure of glucose is shown below.
(a) State the functional groups present in the structure.
(ii) Which of the functional groups would react with warm Fehling's solution?
View Answer & Explanation(ii) the process by which starch is converted to glucose.
(b) The open-chain structure of glucose is shown below.
(a) State the functional groups present in the structure.
(ii) Which of the functional groups would react with warm Fehling's solution?
Question 245:
(a)(i) State three differences between electrovalent compound and covalent compound.
(ii) Name the type of chemical bonding involved in the formation of ammonium ion from ammonia.
(b)(i) Name the quantum numbers which define an electron within an atom.
(ii) State the orbital in which the fifth electron of an atom is most likely to be found. Sketch the shape of the orbital.
(iii) State the period and the group to which the element boron belongs in the Periodic Table.
(c)(i) What is meant by the entropy of a chemical system?
(ii) Calculate the free energy change for a given reaction at 300 K using the following data obtained for the reaction: \(\Delta\) = -710KJ mol\(^{-1}\); \(\Delta\)S = 0.15 KJ mol\(^{-1}\)K\(^{-1}\)
(iii) From your evaluation in (c)(i) above, state whether the reaction is spontaneous or not at the given temperature. Give reason for your answer.
View Answer & Explanation(ii) Name the type of chemical bonding involved in the formation of ammonium ion from ammonia.
(b)(i) Name the quantum numbers which define an electron within an atom.
(ii) State the orbital in which the fifth electron of an atom is most likely to be found. Sketch the shape of the orbital.
(iii) State the period and the group to which the element boron belongs in the Periodic Table.
(c)(i) What is meant by the entropy of a chemical system?
(ii) Calculate the free energy change for a given reaction at 300 K using the following data obtained for the reaction: \(\Delta\) = -710KJ mol\(^{-1}\); \(\Delta\)S = 0.15 KJ mol\(^{-1}\)K\(^{-1}\)
(iii) From your evaluation in (c)(i) above, state whether the reaction is spontaneous or not at the given temperature. Give reason for your answer.