Chemistry, 2007, WASSCE/WAEC MAY/JUNE, Exam, Paper 1 | Objectives

Paper Info

Year :

2007

Title :

Chemistry

Exam :

WASSCE/WAEC MAY/JUNE

Paper 1 | Objectives

11 - 20 of 39 Questions

#	Question	Ans
11.	14.8 g of a salt (z)dissolved in 250 cm³ of distilled water gives a concentration of 0.80 mol dm^-3. Calculate the molar mass of the salt (z). A. 13.5 g mol^-1 B. 18.5 g mol^-1 C. 47.4 g mol^-1 D. 74.0 g mol^-1 Show Content Detailed Solution 250cm³ of distilled water contains 14.8g of salt(z) 1cm³ of distilled water will contain \(\frac{14.8 x 1}{250}\) of salt (z) :. 1000cm³ of distilled water will contain \(\frac{14.8 x 1 x 1000}{250}\) = 59.2g/dm³3 = \(\frac{concentration in g/dm³}{molar mass} 0.80 = \(\frac{59.2}{molar mass}\) molar mass = \(\frac{59.2}{0.80}\) = 74.0 g/mol	D
12.	How many atoms are there in one mole of hydrogen gas? [Avogadro's constant = 6.02 x 10²³mol^-1] A. 1.2 x 10 ²³ B. 6.0 x 10 ²³ C. 1.2 x10 ²⁴ D. 6.0 x 10 ²⁴ Show Content Detailed Solution One mole of hydrogen gas has 6.02 x 10²³ atoms mole concept :. one mole of hydrogen gas will have 6.02 x 02 x 10²³ atoms	B
13.	What is the IUPAC name of the compound represented by the molecular formula NaCIO₄? A. Sodium tetraoxochlorate (l) B. Sodium tetraoxochlorate (IV) C. Sodium tetraoxochlorate (VI) D. Sodium tetraoxochlorate(VII)	D
14.	When air is successively passed through sodium hydroxide solution, alkaline pyrogallol and then concentrated tetraoxosulphate (VI) acid, its remaining components are A. oxygen and water vapour B. oxygen and nitrogen C. carbon (IV) acid and noble gases D. nitrogen and noble gases	D
15.	Which of the following gases is light than air? A. CO₂ B. SO₂ C. HCI D. NH₃	D
16.	Which of the following statements is true of the molecules of a gas under ideal conditions? The molecules A. move at random B. undergo inelastic collisions C. attract each other D. occupy a large volume	A
17.	In which of the following compound (s) will heat be absorbed on adding water?l. KNO\(_3\) II. Concentrated H\(_2\)SO\(_4\) III. NH\(_4\)CI A. I only B. lll only C. l and lll only D. ll and lll only Show Content Detailed Solution KNO\(_3\) and NH\(_4\)Cl both undergo endothermic.	C
18.	Consider the reaction represented by the equation: Ca(OH)_2(aq) + CO _2(g) → CaCO3_(s) + H ₂O_(l) in the reaction above, CO ₂ acts as A. an acidic oxide B. an oxidizing agent C. a basic oxide D. a dehydrating agent	A
19.	Which of the following compounds is a basic salt? A. Mg(NO₃)₂ B. (NH₄)₂SO₄ C. K₄Fe(CN)₆ D. Zn(OH)CI	D
20.	What process is illustrated below? S_(s) ⇌^H₂O⇌ S _(aq) A. Decomposition of a solid B. Melting of a solid C. Formation of saturated solution of a solid D. Sublimation of a solid	C

11.	14.8 g of a salt (z)dissolved in 250 cm³ of distilled water gives a concentration of 0.80 mol dm^-3. Calculate the molar mass of the salt (z). A. 13.5 g mol^-1 B. 18.5 g mol^-1 C. 47.4 g mol^-1 D. 74.0 g mol^-1 Show Content Detailed Solution 250cm³ of distilled water contains 14.8g of salt(z) 1cm³ of distilled water will contain \(\frac{14.8 x 1}{250}\) of salt (z) :. 1000cm³ of distilled water will contain \(\frac{14.8 x 1 x 1000}{250}\) = 59.2g/dm³3 = \(\frac{concentration in g/dm³}{molar mass} 0.80 = \(\frac{59.2}{molar mass}\) molar mass = \(\frac{59.2}{0.80}\) = 74.0 g/mol	D
12.	How many atoms are there in one mole of hydrogen gas? [Avogadro's constant = 6.02 x 10²³mol^-1] A. 1.2 x 10 ²³ B. 6.0 x 10 ²³ C. 1.2 x10 ²⁴ D. 6.0 x 10 ²⁴ Show Content Detailed Solution One mole of hydrogen gas has 6.02 x 10²³ atoms mole concept :. one mole of hydrogen gas will have 6.02 x 02 x 10²³ atoms	B
13.	What is the IUPAC name of the compound represented by the molecular formula NaCIO₄? A. Sodium tetraoxochlorate (l) B. Sodium tetraoxochlorate (IV) C. Sodium tetraoxochlorate (VI) D. Sodium tetraoxochlorate(VII)	D
14.	When air is successively passed through sodium hydroxide solution, alkaline pyrogallol and then concentrated tetraoxosulphate (VI) acid, its remaining components are A. oxygen and water vapour B. oxygen and nitrogen C. carbon (IV) acid and noble gases D. nitrogen and noble gases	D
15.	Which of the following gases is light than air? A. CO₂ B. SO₂ C. HCI D. NH₃	D

16.	Which of the following statements is true of the molecules of a gas under ideal conditions? The molecules A. move at random B. undergo inelastic collisions C. attract each other D. occupy a large volume	A
17.	In which of the following compound (s) will heat be absorbed on adding water?l. KNO\(_3\) II. Concentrated H\(_2\)SO\(_4\) III. NH\(_4\)CI A. I only B. lll only C. l and lll only D. ll and lll only Show Content Detailed Solution KNO\(_3\) and NH\(_4\)Cl both undergo endothermic.	C
18.	Consider the reaction represented by the equation: Ca(OH)_2(aq) + CO _2(g) → CaCO3_(s) + H ₂O_(l) in the reaction above, CO ₂ acts as A. an acidic oxide B. an oxidizing agent C. a basic oxide D. a dehydrating agent	A
19.	Which of the following compounds is a basic salt? A. Mg(NO₃)₂ B. (NH₄)₂SO₄ C. K₄Fe(CN)₆ D. Zn(OH)CI	D
20.	What process is illustrated below? S_(s) ⇌^H₂O⇌ S _(aq) A. Decomposition of a solid B. Melting of a solid C. Formation of saturated solution of a solid D. Sublimation of a solid	C