Federal Board Class IX Chemistry

SECTION “A”

Q.1. Insert the correct option i.e. A/B/C/D in the empty box provided opposite each part. Each part carries one mark. (12)

i. Who was the chemist that formulated the principles of converting solids into liquids and liquids into gases.

• Gibbs
• Jabir Bin Haiyan
• Hess
• Robert Boyle

ii. What type of reaction is the following?

AgNO₃ + NaCl —-> AgCl + NaNO₃ is an example of

• Addition reaction
• Displacement reaction
• Decomposition reaction
• Double Displacement reaction

iii. What is the maximum number of electrons that the d-sub shell in an atom can accommodate?

• 10
• 6
• 2
• 14

iv. What of the elements has the maximum electro negativity value of 4.00?

• Chlorine
• Bromine
• Fluorine
• Cesium

v. What is Magnesium oxide (MgO) an example of?

• Acidic oxide
• Basic oxide
• Amphoteric oxide
• Strong acidic oxide

vi. What is the temperature of a liquid called at which it’s vapour pressure becomes equal to the atmospheric pressure?

• Melting
• Boiling
• Boiling point
• Melting point

vii. What do we call a solution whose concentration is known?

• Saturated Solution
• Colloidal Solution
• Concentrated Solution
• Standard Solution

viii. Who invented the first electronic cell of the world?

• Alessnadro volta
• Nicholoson and Carlisle
• Micheal Faraday
• John Dalton

ix. In which of the following is lactic acid present naturally?

• Sour milk
• Lemon
• Grapes and tamarind
• Stings of honey bee

x. What is the acidity of Ferric hydroxide, Fe(OH)

• 1
• 3
• 4
• 2

xi. What is the pH value of neutral solution?

• 6
• 8
• 12
• 7

xii. What is the branch of chemistry that deals with the heat changes during chemical reactions called?

• Electro chemistry
• Thermo chemistry
• Physical chemistry
• Analytical chemistry

SECTION “B”

Q.2. Attempt any ELEVEN parts. The answer to each part should not exceed 3 to 4 lines. (33)

i. Write balanced equations of the following reactions using symbols and chemical formulas.

a. Magnesium + Copper Sulphate —-> + Magnesium Sulphate (01)
b. Aluminium + Oxygen —-> Aluminium oxide (01)
c. Zinc Nitrate —-> Zinc oxide + Oxygen + Nitrogen per Oxide (01)

ii. Hydrogen and oxygen combine to form two types of oxides ‘A’ and ‘B’. ‘A’ contains 2g of hydrogen with 16g of oxygen whereas ‘B’ contains 2g of hydrogen with 32g of oxygen.

a. State the law governing the formation of two oxides from the same element. (01)
b. Write the formulas for oxides A and B. (01)
c. Define chemical formula. (01)

iii. A chemical bond is the force of attraction between atoms, which holds them in the form of molecule or a compound.

a. What type of bond is formed in the following:

Na + Cl —-> Na+ + Cl-

b. Why does magnesium metal have a higher melting point than sodium metal? Give reasons. (02)

iv. Solid substances consist of ions, atoms and molecules.

a. Why does sodium chloride (NaCl) have a very high melting point but ice has a low melting point. (01)
b. What is meant by ‘Sublimation’? (01)

v. The intermolecular forces are the forces of attraction between the molecules of a compound.

a. What type of intermolecular force is present in hydrogen fluoride? (1/2 + 1/2)
b. Why does hydrogen gas diffuse through a porous pot faster than carbon dioxide? (01)

vi. The process of dissolving a solute in water is called hydration.

a. Draw the hydrated sodium and chloride ions. (02)
b. Define a freezing mixture. (01)

vii. (a) How much solution of sodium chloride of concentration 4% by mass will contain 3g of sodium chloride? (02)
b. What is meant by ‘solvent’? (01)

viii. In the Zinc-carbon dry cell, Zinc-container consists of a moist mixture of ammonium chloride manganese-dioxide and powder carbon.

a. Write the chemical reactions talking place at the anode and the cathode of a dry cell. (01)
b. Write one additional advantage of lead storage battery over the zinc carbon dry cell. (01)

ix. Acetic acid is a acid.

a. Why is acetic acid monobasic but phosphoric acid is tribasic? Explain. (01)
b. Write the chemical formulas of the following: (Potash Alum, Carnalite) (01)

x. (a) Identify the category of the following salts.

Magnesium Chloride, Sodium Sulphate, Pb(OH)NO₃, K₂SO₄Fe₂(SO₄)₃24H₂O

xi. Give two uses of copper sulphate. In the chemical reaction (01)

HCl(aq) + NaOH(aq) —-> H₂O(l) + Na+ + Cl-(aq)

a. Name the type of the chemical reaction. (01)
b. Define spectator ions. (01)
c. What is meant by exothermic reaction? (01)

xii. Jabir Bin Haiyan is known as the father of chemistry.

a. Write down of his major contributions to chemistry. (01)

xiii. Covalent bond is formed by the mutual sharing of an electron pair provided by the bonded atoms.

a. What type of bond is formed between Ammonia (NH₃) and Boron Trifluoriae BF₃? Explain. (02)
b. Write down properties of covalent compounds. (01)

xiv. Metallic bond is a type of chemical bond.

a. Why are metals good conductors of electricity? (01)
b. Define the Octet Rule. (01)
c. Justify that hydrogen chloride (HCl) is a polar. molecule. (01)

xv. Molecule and compounds are represented by chemical formulas.

a. What is meant by molecular formula? (01)
b. Write the empirical formula of?
(Glucose, Hydrogen Per Oxide) (01)

c. Calculate the molecular mass KMnO
(Atomic Masses: O=16, K=39, Mn=54 (01)

SECTION “C”

NOTE: Attempt any TWO questions. (20)

Q.3. The central heavy part of an atom is called ‘Nucleus’.

a. Explain Rutherford’s atomic model. (03)
b. What are the defects in Rutherford’s atomic model? (02)
c. Write three postulates of Bohr’s atomic model. (03)
d. Draw the electronic configuration of
i. 24 Mg
..12

ii. 35 Cl
.. 17

Q.4. The statement, “Properties of an element are a periodic function of their atomic numbers”.

a. Why is the present form of modern periodic table called the ‘long form of periodic table’. (02)
b. Write two advantages of modern periodic table over the Mendeleev’s periodic table. (02)
c. State the two important features of modern periodic table regarding the:
i. Number periods, ii. Number of blocks. (02)
d. Give reasons for the variation of atomic radii and ionization energy in a period from left to right according to modern periodic table.(02 + 02)

Q.5. Micheal Faraday published two laws about electrolysis.

a. State these two laws with their mathematical forms. (02 + 02)
b. Define electrolysis. Explain the electrolysis of an aqueous solution of sodium chloride. (01 + 02 + 02)
c. What is meant by “Electroplating”? (01)