Chemistry Past Questions And Answers
(a) Define the following terms:(i) Saturated solution; (ii) Solubility.
(b) In an experiment to determine the solubility of a given salt Y, the following data were provided:
Mass of dry empty dish = 7.16 g
Mass of dish + saturated solution of salt Y = 17.85 g
Mass of dish + salt Y = 9.30 g Temperature of solution = °C
Molar mass of salt Y = 100
Density of solution Y = 1.00 g cm\(^{-3}\) Calculate the solubility of salt Y in
(i) g dm\(^{-3}\) of solution, (ii) mol dm\(^{-3}\) of solution.
(c) State the type of bond broken on melting each of the following substances: (i) NaCI\(_{(s)}\) (ii) CO\(_{2(s)}\) (iii) SiO\(_{2(s)}\) (iv) Al\(_{(s)}\)
(d) Explain the following observations: (i) the chemical reactivity of alkali metals increases down the group; (ii) Mg has higher melting point than Na; (iii) K is a better reducing agent than Na.
(e)(i) What are isotopes? (ii) Lithium exists as \(^6_3\)Li and \(^7_3\)Li in the ratio 2:25. Calculate the relative atomic mass of the lithium.
View Discussion (0)WAEC 2007 THEORYWhat is the shape of a molecule of CCI4?
- A. Pyramidal
- B. Tetrahedral
- C. Trigonal planar
- D. Linear
The ions X-and Y+ are isoelectronic, each containing a total of 10 electrons. How many protons are in the nuclei of the neutral atoms of X and Y respectively?
- A. 10 and 10
- B. 9 and 9
- C. 11 and 9
- D. 9 and 11
(a) State whether entropy increases or decreases during each of the following processes
(i) condensation of steam;
(ii) melting of wax;
(iii) dissolution of sugar in water;
(iv) abscas on charcoal.
(b) What deduction can be made in each case given that the value of the free energy change for a particular reaction is:
(i) zero;
ii) negative
View Discussion (0)WAEC 1994 THEORYIf X is a group lll element, its oxide would be represented as
- A. X3O2
- B. X3O
- C. X2O3
- D. XO3
In which of the following are water molecules in the most disorderly arrangement?
- A. Ice at -10°C
- B. Ice at 0°C
- C. Water at 100°C
- D. Steam at 100°C
The constituents of baking powder that makes the dough to rise is
- A) NaHCO3
- B) NaOH
- C) Na2CO3
- D) NaCl
An element that can exist in two or more different structural forms which possess the same chemical properties is said to exhibit
- A) polymerism
- B) isotropy
- C) isomorphism
- D) allotropy
Chlorine, consisting of two isotopes of mass numbers 35 and 37, has an atomic mass of 35.5. The relative abundance of the isotope of mass number 37 is?
- A. 20
- B. 25
- C. 50
- D. 75
The purity of a solid sample can best be determined by its
- A. boiling point
- B. melting point
- C. conductivity
- D. solubility