chem module

8/3/2019 Chem Module

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Chapter 1 Chapter 3

Objective Questions

1.

From the above statement of hypothesis, which one of the following is the responding

variable?

A Hydrogen ion

B Concentration of hydrogen ion

C pH value

D pH value and hydrogen ion

2. W, X, Y and Z are the steps for investigation in a scientific method.

Which of the following showed the correct order?

A W, Y, X, Z C Y, X, Z, W

B X, Y, Z, W D Z, X, Y, W

3. The graph shows the temperature against time for a sample of lead when it is heated until

it melts and then cooled down to room temperature. Which of the following portion of

the graph labeled A, B, C and D represents the melting process?

4. Which of the following statements are true about the kinetic theory of matter?

I Particles are always moving and vibrating.

II The particles in liquid move slower than the particles in gas.

III The speed of particles will be greater if more energy is supplied.

IV The movement of particles in solid is mainly vibration.

A I and II C I, II and IV

B II and IV D I, II, III and IV

5. A substance exists in gaseous state at temperature of 40oC. Which of the following is the

likely melting point and boiling point of X?

The higher the concentration of hydrogen

ions, the lower the pH value.

W Collect data

X Control variablesY Make hypothesis

Z Conduct experiment


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A 8 B 18 C 22 D 32

9. Oxygen has 3 isotopes namely oxygen-16, oxygen-17 and oxygen-18. What are the

similarities between these 3 isotopes?

I Chemical properties

II Physical propertiesIII Nucleon number

IV Number of electrons

A I and III only C II and III only

B I and IV only D I, III and IV only

10. The chemical formula for potassium hexacyanoferrate(III) is K3Fe(CN)6. What is its

relative formula mass? [Relative atomic mass: C=12; N=14; K=39; Fe=56]

A 121 C 251

B 199 D 329

1. C 2. C 3. B 4. D 5. D 6. B 7. C 8. B 9. B 10. DStructured Questions

1. Table 1 shows the incomplete information about 4 atoms namely J, K, L and M.

Atom Proton Number Nucleon Number Electronic Structure

J 12 24

K 35 2.8.7

L 39 2.8.8.1

M 20 40

Table 1i) Name 3 subatomic particles that are found in an atom.

ii) Complete the above table by filling the missing proton numbers and electronic

structures.

iii) Name two atoms in Table 1 that have the same number of valence electrons.

[Avogadro constant: 6.02 x 1023 mol-1 ; Relative atomic mass: C=12; O=16; Cu=64; Al=27]

2. a) Find the number of atoms in 5 mole of copper, Cu. [2m]

b) Find the number of atoms in 2.5 mole of nitrogen gas, N2. [3m]

c) Calculate the molar mass of aluminium oxide, Al2O3. [1m]

d) Find the mass of 1.8 mole of copper(II) oxide, CuO. [2m]

e) Find the number of moles of 35g of carbon monoxide gas, CO. [2m]

3. Information below shows the results of the experiment.


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Determine the empirical formula of the oxide of M:

[Relative atomic mass of O =16 , M = 207 ]

4. The information below is about hydrocarbon J

Empirical formula of J is CH2Mass of 1 mole of J = 28 g

Determine the molecular formula for hydrocarbon J.

[Relative atomic mass of C =12 , H = 1 ]

5. Solid Q has melting point of 85 0C and boiling point of 150 0C. A boiling tube containing

solid Q is heated at room temperature until 180 0C.

(i) Sketch a graph of temperature against time during the heating.

(ii) Draw the arrangement of particles of substance Q at 50 OC.

Answer:

1. a) Proton, electron and neutron

b)

Atom Proton Number Nucleon Number Electronic Structure

J 12 24 2.8.2

K 17 35 2.8.7L 19 39 2.8.8.1

M 20 40 2.8.8.2

c) J and M

2. a) 3.01 x 1024 atoms

b) 3.01 x 1024 atoms

c) 102 g mol-1

d) 144 g

e) 1.25 mol

3. Empirical formula is MO

4. C2H45. (i)

Mass of combustion tube + porcelain dish = 52.34 g

Mass of combustion tube + porcelain dish + oxide of M = 105.86 g

Mass of combustion tube + porcelain dish + M = 102.02 g

Time/ s

Temperature/0

C

150

85

180 _


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(ii)

Essay Questions

1. Use one example to compare and contrast isotopes.

2. Explain why temperature remains constant from 2nd to 8th minute for substance X which

has a melting point 80oC..

Answer

1. Isotopes: Chlorine-35 and chlorine-37

Characteristics Chlorine-35 Chlorine-37

Proton number 17 17

Nucleon number 35 37

Number of protons 17 17

Number of electrons 17 17

Number of neutrons 18 20

Electron arrangement 2.8.7 2.8.7

Number of valence electron 7 7


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2. Because the heat lost to the surroundings is exactly balanced by the heat energy

liberated as the particles attract one another to form solid.

chem module

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