(a) In Kenya, sodium carbonate is extracted from trona at Lake Magacli.
(i) Give the formula of trona. 
(ii) Name the process of extracting sodium carbonate from trona. 
(b) The flow chart in Figure 5 summarises the steps involved in the production of sodium carbonate.
Use it to answer the questions that follow.

​(i) Name the process illustrated in Figure 5. 
(ii) Identify the starting raw materials required in the production of sodium carbonate. 
(iii) Write equations for the two reactions that occur in the carbonator. 
(iv) Name two substances that are recycled. 
(v) Identify:
Solid X; 
Process W. 
(vi) Write an equation for the reaction that produces solution Z. 
(vii) Apart from softening hard water, state two other uses of sodium carbonate.
 

Figure 2 is a section of the periodic table. Study it and answer the questions that follow. The letters do not represent the actual symbols of elements.

(a) (i) Select elements which belong to the same chemical family.
(ii) Write the formulae of ions for elements in the same period.
(b) The hrst ionisation energies of two elements K and M at random are 577 kJ/mol and 494 kJ/mol 
(i) Write equations for the 1ˢᵗ ionisation energies for elements K and M and indicate their energies.
(iii) Write the formula of the compound formed when L and I react.
(iv) Give one use of elemcnt V.
(c) (i) State anothcr group that G can be placcd in Figure 1. Explain. 
(ii) How do the reactivity of elements J and K compare? Explain. 
(d) (i) Elements L and M form chlorides.
​Complete the following table by writing the formulae of each chloride and state the nature of the solutions.

​(ii) The chloride of element M vapourises easily while its oxide has a high melting point. Explain.

 Explain why a solution of sodium chloride Conducts electricity while that of sugar does not.

 Figure 5 represents a grid that is part of the periodic table. Study it and answer the questions that follow. The letters are not the actual symbols of the elements.

(a) Write the electron arrangement of element C. 
(b) On the grid provided, show with a tick (✓) the position of element D whose atomic number is 18. 
(c) Element E is more reactive than A. Explain. 

 You are provided with solid potassium hydrogen carbonate. Describe how a solid sample of  potassium nitrate can be prepared.

(a) Element U has atomic number 12 while element V has atomic number 16. How do the melting points of their oxides compare? Explain. 

(a) Explain why it is not advisable to prepare a sample of carbon(IV) oxide using barium carbonate and dilute sulphuric(VI) acid. 
(b) State a method that can be used to collect dry carbon(IV) oxide gas. Give a reason.

W is a colourless aqueous solution with the following properties:

• I It turns blue litmus paper red.
• II On addition of cleaned magnesium ribbon, it gives off a gas that burns with a pop sound.
• III On addition of powered sodium carbonate, it gives off a gas which forms a precipitate with calcium hydroxide solution.
• IV When warmed with copper(II) oxide powder, a blue solution is obtained but no gas is given off
• V On addition of aqueous barium chloride, a white precipitate is obtained.

(a) (i) State what properties (I) and (III) indicate about the nature of W. 
(ii) Give the identity of W. 
(iii) Name the colourless solution formed in (II) and (III). 
(iv) Write an ionic equation for the reaction indicated in (V).
(b) Element V conducts electricity and melts at 933K. When chlorine gas is passed over heated V, it forms a vapour that solidifies on cooling. The solid chloride dissolves in water to form an acidic
solution. The chloride vapour has a relative molecular mass of 267 and contains 19.75% of V. At a higher temperature, it dissociates to a compound of relative molecular mass 133.5. When aqueous
sodium hydroxide is added to the aqueous solution of the chloride, a white precipitate is formed which dissolves in excess alkali. (V = 27.0 ; CI = 35.5)
(i) Determine the:

• I empirical formula 
• II molecular formula 

(ii) Draw the structure of the chloride vapour and label the bonds. 
(iii) Write an equation for the reaction that form a white precipitate with sodium hydroxide. 

In terms of structure and bonding, explain why graphite is used as a lubricant in machines.

Figure 6 shows part of the periodic table. The letters are not the actual symbols of the elements. Stud it and answer the questions that follow.

​(a) Write an equation for the reaction between M and K. 
(b) Select the element which can form an ion with a charge of +3. 
(c) An element J has atomic number 15. Indicate with a tick (✓), on the part of the periodic table the position of J.

​The atomic numbers of some elements P, Q, R and S are 6, 8, 12 and 17 respectively.
(a) Draw the dot (•) and cross (X) diagrams for the compounds formed when:
(i) R and Q react 
(ii) P and S react. 
(b) Explain why the melting point of the compound formed by P and S is lower than that formed by R and Q.

​Starting with copper, describe how a pure sample of copper(II) carbonate can be prepared.

Table 1 shows the atomic numbers and the first ionisation energies of three elements. The letters are not actual symbols of the elements. Use it to answer the questions that follow.

​(a) Explain the trend in first ionisation energy from A to C. 
(b) Write the electronic configuration for the ion of C.