Chemistry, 2006, WASSCE/WAEC MAY/JUNE, Exam, Paper 1 | Objectives

Paper Info

Year :

2006

Title :

Chemistry

Exam :

WASSCE/WAEC MAY/JUNE

Paper 1 | Objectives

1 - 10 of 27 Questions

#	Question	Ans
1.	How many orbitals are in the d-sub shell? A. 1 B. 3 C. 5 D. 7	C
2.	An element X has isotopic masses of 6 and 7. if the relative abundance is 1 to 12.5 respectively, what is the relative atomic mass of X? A. 6.0 B. 6.1 C. 6.9 D. 7.0 Show Content Detailed Solution Contribution by isotope 6 = 6 x 1 = 6 contribution by isotope 7 = 7 x 12.5 = 87.5 This contribution is made by 1 + 12.5 = 13.5 atoms Relative atomic mass of = 87.5 + 6 = 93.5/13.5 = 6.9	C
3.	An atom ²³⁸₉₂X decays by alpha particle emission to give an atom Y. The atomic number and mass number of Y are A. 90 and 234 respectively B. 91 and 238 respectively C. 92 and 236 respectively D. 93 and 238 respectively Show Content Detailed Solution 238₉₂ X 234 ₉₀Y + ^{4 ₂ He Atomic number is 90 while mass number is 234}	A
4.	If 1 mole of sodium contains 6 x 10²³ atoms, how many atoms are contained in 0.6 g of sodium? [Na = 23] A. 1.56 x 10²³ B. 1.56 x 10²² C. 3.6 x 10²³ D. 3.6 x 10²² Show Content Detailed Solution 23g of sodium contain 6 x 10₂₃ atoms :. 0.6g of sodium will contain \(\frac{0.6 x 6 x 10²³}{23}/) = 1.56 x 10²²	B
5.	If 20 cm³ of distilled water is added to 80cm ³ of 0. 50 mol dm^-3 hydrochloric acid, the new concentration of the acid will be A. 0.10mol dm^-3 B. 0.20mol dm^-3 C. 0.40mol dm^-3 D. 2.00mol dm^-3 Show Content Detailed Solution C₁ x 100 = 0.5 x 80 C₁ = \(\frac{0.5 x 80}{100}/) = \(\frac{4}{10}/) = 0 . 40mol/dm^-3	D
6.	Consider the reaction represented by the equation. 2NaHCO_3(s) \(\rightarrow\) 2Na₂CO _3(S) + CO _2(g) + H₂O_(g) what volume of carbon (IV)oxide at s.t.p is evolved when 0. 5 moles of NaHCO₃ is heated? [Molar volume = 22.4 dm³ at s.t. p] A. 1.12dm³ B. 2.24dm³ C. 5.6dm³ D. 56.0dm³ Show Content Detailed Solution 2NaHCO_3(s) \(\rightarrow\) 2Na₂CO _3(S) + CO _2(g) + H₂O_(g) 2 moles of 2NaHCO_3(s) produces 22.4dm³ of CO₂ 0.5 moles of 2NaHCO₃ will produce \(\frac{0.5 \times 22.4}{2}\) = \(\frac{11.2}{2}\) = 5.6 dm³	C
7.	Considered the reaction: H⁺_(aq) + OH ^- _(aq) → H₂O _(l). The energy change taking place in the reaction above is enthalpy of A. formation B. hydration C. neutralization D. solution	C
8.	Which of the following processes is an endothermic reaction? A. Dissolving NH₄CI crystals in water B. Addition of concentrated H₂SO₄ C. Dissolving NaOH pellets in water D. Passing SO₃ gas into water	A
9.	Which of the following aqueous methods cannot be used to distinguish between a strong acid and a a weak acid? A. Conductivity measurement B. Measurement of pH C. Measurement of heat of neutralization D. Action on starch iodide paper	D
10.	The indicator used in neutralizing CH₃COOH and NaOH solution has pH range of A. 3-5 B. 7-8 C. 8-10³ D. 10-12	C

1.	How many orbitals are in the d-sub shell? A. 1 B. 3 C. 5 D. 7	C
2.	An element X has isotopic masses of 6 and 7. if the relative abundance is 1 to 12.5 respectively, what is the relative atomic mass of X? A. 6.0 B. 6.1 C. 6.9 D. 7.0 Show Content Detailed Solution Contribution by isotope 6 = 6 x 1 = 6 contribution by isotope 7 = 7 x 12.5 = 87.5 This contribution is made by 1 + 12.5 = 13.5 atoms Relative atomic mass of = 87.5 + 6 = 93.5/13.5 = 6.9	C
3.	An atom ²³⁸₉₂X decays by alpha particle emission to give an atom Y. The atomic number and mass number of Y are A. 90 and 234 respectively B. 91 and 238 respectively C. 92 and 236 respectively D. 93 and 238 respectively Show Content Detailed Solution 238₉₂ X 234 ₉₀Y + ^{4 ₂ He Atomic number is 90 while mass number is 234}	A
4.	If 1 mole of sodium contains 6 x 10²³ atoms, how many atoms are contained in 0.6 g of sodium? [Na = 23] A. 1.56 x 10²³ B. 1.56 x 10²² C. 3.6 x 10²³ D. 3.6 x 10²² Show Content Detailed Solution 23g of sodium contain 6 x 10₂₃ atoms :. 0.6g of sodium will contain \(\frac{0.6 x 6 x 10²³}{23}/) = 1.56 x 10²²	B
5.	If 20 cm³ of distilled water is added to 80cm ³ of 0. 50 mol dm^-3 hydrochloric acid, the new concentration of the acid will be A. 0.10mol dm^-3 B. 0.20mol dm^-3 C. 0.40mol dm^-3 D. 2.00mol dm^-3 Show Content Detailed Solution C₁ x 100 = 0.5 x 80 C₁ = \(\frac{0.5 x 80}{100}/) = \(\frac{4}{10}/) = 0 . 40mol/dm^-3	D

6.	Consider the reaction represented by the equation. 2NaHCO_3(s) \(\rightarrow\) 2Na₂CO _3(S) + CO _2(g) + H₂O_(g) what volume of carbon (IV)oxide at s.t.p is evolved when 0. 5 moles of NaHCO₃ is heated? [Molar volume = 22.4 dm³ at s.t. p] A. 1.12dm³ B. 2.24dm³ C. 5.6dm³ D. 56.0dm³ Show Content Detailed Solution 2NaHCO_3(s) \(\rightarrow\) 2Na₂CO _3(S) + CO _2(g) + H₂O_(g) 2 moles of 2NaHCO_3(s) produces 22.4dm³ of CO₂ 0.5 moles of 2NaHCO₃ will produce \(\frac{0.5 \times 22.4}{2}\) = \(\frac{11.2}{2}\) = 5.6 dm³	C
7.	Considered the reaction: H⁺_(aq) + OH ^- _(aq) → H₂O _(l). The energy change taking place in the reaction above is enthalpy of A. formation B. hydration C. neutralization D. solution	C
8.	Which of the following processes is an endothermic reaction? A. Dissolving NH₄CI crystals in water B. Addition of concentrated H₂SO₄ C. Dissolving NaOH pellets in water D. Passing SO₃ gas into water	A
9.	Which of the following aqueous methods cannot be used to distinguish between a strong acid and a a weak acid? A. Conductivity measurement B. Measurement of pH C. Measurement of heat of neutralization D. Action on starch iodide paper	D
10.	The indicator used in neutralizing CH₃COOH and NaOH solution has pH range of A. 3-5 B. 7-8 C. 8-10³ D. 10-12	C