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SS1: CHEMISTRY - 1ST TERM

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  1. Introduction to Chemistry and Laboratory Apparatus | Week 1
    5Topics
    |
    1 Quiz
  2. Nature of Matter | Week 2
    3Topics
    |
    1 Quiz
  3. Separation Techniques I | Week 3
    1Topic
    |
    1 Quiz
  4. Separation Techniques II | Week 4
    5Topics
    |
    1 Quiz
  5. Particulate Nature of Matter I | Week 5
    5Topics
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    1 Quiz
  6. Particulate Nature of Matter II | Week 6
    9Topics
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    1 Quiz
  7. Symbols, Formulae & Oxidation Number | Week 7
    7Topics
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    1 Quiz
  8. Laws of Chemical Combination | Week 8
    4Topics
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    1 Quiz
  9. Chemical Equation & Chemical Combination (Chemical Bonding) I | Week 9
    4Topics
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    1 Quiz
  10. Chemical Combination (Chemical Bonding) II | Week 10
    4Topics
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    1 Quiz
  11. Chemical Combination (Chemical Bonding) III & Shapes of Covalent Molecules | Week 11
    3Topics
    |
    1 Quiz
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Hydrated Salts are salts containing water of crystallization. The number of water molecules is indicated by mono, di, tri, tetra, penta etc. according to the number of water of crystallization.

In naming the corresponding anhydrous salt i.e without molecules of water, the salt is first named, followed by a full-stop, then the number of water molecules of water is written down. Example:

IUPAC NAMEHYDRATED SALT
Sodium trioxocarbonate (IV) decahydrateNa2CO3.10H2O
Copper(II) tetraoxosulphate (VI) pentahydrateCuSO4.5H2O
Cobalt (II) Chloride hexahydrateCOCl2.6H2O

Theory Questions

1. Write down the formulae of the following: 

(i) Ozone    
(ii) Hydrogen sulphate 
(iii) Magnesium tetraoxosulphate(VI)  
(iv)Oxygen molecule 
 (v) Bromine molecule 

View Answer

2. Calculate the Oxidation number of the underlined elements

(a) H2SO4          
(b) CO2       
(c) NaH        
(d) Cr2O           
(e) FeCl2       
(f) NaMnO4

View Answer

3. Give the IUPAC name of the following compounds

(a) MgO            
(b) NaSO4
(c) FeO3          
(d) Al2O3 

View Answer

4.

(a) Give the symbols of the following elements:

(i) Silicon          
(ii) Chlorine 
(iii) Silver          
(iv) Potassium

(b) Name the elements with the following symbols:

(i) Sn         
(ii) Br
(iii) Cr          
(iv) Be

View Answer

Theory Question 1

1. Write down the formulae of the following: 

(i) Ozone   

Answer: O3  

(ii) Hydrogen sulphate   

Answer: Hydrogen Sulphate
H+1 SO4-1
H+ SO4

(iii) Magnesium tetraoxosulphate(VI)  

Answer:

Mg+2 SO4-1

MgSO4 T.H2O

(iv) Oxygen molecule

Answer:  O2

(v) Bromine molecule 

Answer:  Br2

Theory Question 2

Calculate the Oxidation number of the underlined elements

(a) H2SO4  

Solution:

(1 x 2) + S + (-2 x 4) = 0

2 + S – 8 = 0

S – 6 = 0

S = +6

The oxidation number of Sulphur (S) in H2SO4  = +6

        
(b) CO2   

Solution:

C + (2 x -2) = 0

C – 4 = 0

C = +4

The oxidation number of carbon (C) in CO2 = +4

    
(c) NaH      

Solution:

Na + (-1) = 0

Na – 1 = 0

Na = +1

Note – H is an hydride; hence oxidation number is -1.

The oxidation number of sodium (Na) in NaH is +1.

  
(d) Cr2O   

Solution:

2Cr + (-2) = 0

2Cr – 2 = 0

2Cr = 2

Cr = \( \frac{2}{2} \)

Cr = +1.

The oxidation number of chromium (Cr) in Cr2O is +1

        
(e) FeCl2  

     
(f) NaMnO4

Solution:

+1 + Mn + (-2 x 4) = 0

1 + Mn – 8 = 0

Mn – 7 = 0

Mn = +7

The oxidation number of Manganese (Mn) in NaMnO4 is +7

Theory Question 3

3. Give the IUPAC name of the following compounds

Answer:

(a) MgO – Magnesium oxide       
(b) NaSO4   Sodium Sulphate
(c) FeO3  Iron (III) oxide         
(d) Al2O3  Aluminium oxide

Theory Question 4

(a) Give the symbols of the following elements:

(i) Silicon – ‘S’       
(ii) Chlorine – ‘Cl’
(iii) Silver  – ‘Ag’        
(iv) Potassium – K’

(b) Name the elements with the following symbols:

(i) Sn  – Tin       
(ii) Br – Bromine
(iii) Cr  – Chromium         
(iv) Be – Beryllium

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