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Part I

1. Give an example of a metal which
   (i) is a liquid at room temperature.
   (ii) can be easily cut with a knife.
   (iii) is the best conductor of heat.
   (iv) is a poor conductor of heat.

Ans: i) Murcury
ii) sodium
iii) Silver
iV) Lead

2. Explain the meanings of malleable and ductile.

Ans: Malleable means when a metal is able to form sheets when it is beaten, and ductility means when a metal has ability to form thin wires when beaten.

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Part II

1. Why is sodium kept immersed in kerosene oil?

Ans: Sodium is kept immersed in kerosene oil because sodium is highly reactive, when sodium comes in contact with air, it forms sodium oxide very quickly.

2. Write equations for the reactions of
(i) iron with steam
(ii) calcium and potassium with water

Ans: i) Iron reacts with steam(water vapour) and produces iron oxide and hydrogen gas.
Fe + H2O -> FeO + H2
ii) Calcium reacts with water forms calcium hydroxide and H2 gas.
Ca + H2O -> Ca(OH)2 + H2
When Potassium reacts with water will form potassium hydroxide and H2 gas.
K + H2O -> KOH + H2

3. Samples of four metals A, B, C and D were taken and added to the
following solution one by one. The results obtained have been tabulated
as follows.

Metal	Iron(II) Sulphate	Copper(II) sulphate	Zinc sulphate	Silver nitrate
A	No Reaction	Displacement
B	Displacement		No Reaction
C	No Reaction	No Reaction	No Reaction	Displacement
D	No Reaction	No Reaction	No Reaction	No Reaction

Use the Table above to answer the following questions about metals
A, B, C and D.
(i) Which is the most reactive metal?
(ii) What would you observe if B is added to a solution of Copper(II) sulphate?
(iii) Arrange the metals A, B, C and D in the order of decreasing reactivity.

Ans: How to identify the order of reactivity of metals A B C D: 
As we know, according to reactivity series the sequence is Zinc (most reactive) > Iron > Copper > Silver (least reactive).

Metal D is having reaction with all 4 solution but not reacting with any one of the four solution, so it is least reactive.

Metal C is also having reaction with all 4 solution but only reacting with silver, which is least in the above given solution. so we can say that C is more reactive than D and least reactive than A and B.

Metal B is having reaction with 2 solution Zinc sulphate and Iron(II) Sulphate and no reaction with zinc and displacing iron, that means it can displace iron , copper and silver. So it is more reactive than C and D.

Metal A is having reaction with iron and copper, where it is giving no reaction with iron, so we can say that it is less reactive than B. And it is replacing copper, so we can say it is more reactive than C.


i) B is the most reactive metal.
ii) When B is added to copper sulphate solution, it performs displacement reaction.
iii) The order of decreasing reactivity : B > A > C > D

4. Which gas is produced when dilute hydrochloric acid is added to a reactive metal? Write the chemical reaction when iron reacts with dilute H₂SO₄.

Ans: When a metal is reacted with acid it forms a salt and release hydrogen gas (H2).
Chemical Reaction: Iron reacts with dilute H2SO4
Fe + H2SO4 -> FeSO4 + H2

5. What would you observe when zinc is added to a solution of iron(II) sulphate? Write the chemical reaction that takes place.

Ans: As Zinc is more reactive than iron, so it will replace the iron from iron sulphate solution and forms zinc sulphate solution. It will be a displacement reaction.
Zn(s) + FeSO4(aq) -> ZnSO4(aq) + Fe(s)

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Part III

1 (i) Write the electron-dot structures for sodium, oxygen and magnesium.
(ii) Show the formation of Na₂O and MgO by the transfer of electrons.
(iii) What are the ions present in these compounds?

Ans: i)To write the electron-dot structure we need to find atomic number of the element, then write the electronic configuration and place the no. of dots equal to the no. of electrons present in the last shell.

For Sodium: 
Atomic no. = 11
electronic configuration = 2,8,1
we have 1 electron in last shell. So show 1 dot along with Symbol like

Na•

For Oxygen:
Atomic no. = 16
electronic configuration = 2,8,6
we have 6 electron in last shell. So show 6 dot along with Symbol like
 . .
: O :

For Magnesium:
Atomic no. = 12
electronic configuration = 2,8,2
we have 6 electron in last shell. So show 2 dot along with Symbol like

Mg:

ii)The ionic compound sodium oxide (Na2O) is formed by the transfer of electrons from sodium to oxygen(sodium loose 1 electron and give to oxygen):
2Na -> 2Na+ + 2e-
O2(g) + 4e⁻ → 2O²⁻(aq)

The resulting ions in sodium oxide are Na⁺ cations and O²⁻ anions.

The ionic compound magnesium oxide (MgO) is formed by the transfer of electrons from magnesium to oxygen(magnesium loose 2 electrons to give oxygen):

Mg(s) → Mg²⁺(aq) + 2e⁻
O2(g) + 4e⁻ → 2O²⁻(aq)

The ions present in magnesium oxide are Mg²⁺ cations and O²⁻ anions.

iii)The ions present in Na2O are:
sodium ion -> Na+
Oxygen ion -> O2-

The ions present in MgO are:
Magnesium ion -> Mg2+
Oxygen ion -> O2-

2. Why do ionic compounds have high melting points?

Ans: The ionic compounds have high melting points due to the strong electrostatic forces of attraction between the positively charged ions (cations) and negatively charged ions (anions) that make up these compounds. These electrostatic forces are called ionic bonds or electrovalent bonds.

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Part IV

1. Define the following terms.
(i) Mineral (ii) Ore (iii) Gangue

Ans: Mineral : A mineral is a naturally occurring inorganic substance with a specific chemical composition and a specific structure. 
Ore : An ore is a naturally occurring rock or mineral deposit that contains a valuable substance (usually a metal or mineral) that can be economically extracted and processed.
Gangue : Gangue refers to the non-valuable or waste material that surrounds or is mixed with the ore in a mineral deposit. 

2. Name two metals which are found in nature in the free state.

Ans: Gold and Silver, the least reactive metals in the reactivity series are found in free state.  

3. What chemical process is used for obtaining a metal from its oxide?

Ans: Reduction is the chemical process used to obtain a metal from its oxide. Respective reducing agent is used to obtain the metal like carbon, zinc, and many other. Whichever is highly reactive than the metal we are extracting, we can use that as reducing agent.

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Part V

1. Metallic oxides of zinc, magnesium and copper were heated with the
following metals. In which cases will you find displacement reactions taking place?

Metal	Zinc	Magnesium	Copper
Zinc Oxide
Magnesium Oxide
Copper Oxide

Ans: As in reactivity series, we have metals in decreasing reactivity sequence as
Magnesium -> Zinc -> Copper. 
As Magnesium is highly reactive then others then it will displace Zinc from zinc oxide and copper from copper oxide.
Whereas Zinc will displace only copper from copper oxide.
And Copper is least reactive so it cannot replace any one of them.

2. Which metals do not corrode easily?

Ans: Metals which are lower in reactivity series are the metals which do not corrode easily, as they do not react easily.
Best example is Gold and Platinum

3. What are alloys?

Ans: An alloy is a homogeneous mixture(components are uniform in the whole solution) of two or more metals, or a metal and a non-metal.

For Example: Iron is commonly used, but it's too soft when pure and can stretch easily when heated. Adding a tiny bit of carbon, makes it strong and hard. When we mix iron with nickel and chromium, we create stainless steel, which is hard and does not rust.