THE UNITED REPUBLIC OF TANZANIA NATIONAL EXAMINATION COUNCIL

CHEMISTRY FTNA 2011

(i) Isotopes are atoms of the same element that have different:

1.  Atomic number  
2.  Electron arrangement
3. Mass number    
4. Protons

   (ii) When substance A and substance B react to produce a new substance C, the reactants A and B are said to:

1. Be miscible    
2. Form a mixture
3. Form a solution C
4. Undergo chemical change

    (iii) In the formula of the compound F₂K₃ the valences of F and K are respectively:

1. 2 and 3     
2. 3 and 2
3. 4 and 6         
4. 6 and 4

    (iv)  The process by which water is converted into water vapour or steam is called:

1. Condensation
2. Evaporation
3. Precipitation
4. Transpiration

     (v) In the Bunsen burner a sooty flame is most likely to be formed when the:

1. Air holes are fully closed 
2. Air holes are opened
3. Flame is noisy
4. Flame is smaller and hotter

    (vi)  The best way to separate a mixture of iodine and iron fillings is by:

1. Decantation
2. Evaporation to dryness 
3. Ractional distillation
4. Sublimation

     (vii) The choice of the source of heat depends on the:

1. Colour of the flame
2. Quantity of heat produced
3. Substance to be burned or boiled
4. Type and shape of flame

    (viii) When oxygen combines with metals they:

1. Form metallic oxides 
2. Form precipitates 
3. Rust
4. Sublime

    (ix)  The pair elements which is most likely to form a covalent bond when  they react together is:

1. Carbon and oxygen
2. Magnesium and potassium
3. Nitrogen and aluminium
4. Sodium and oxygen

    (x) A calcium ion (Ca²+) differs from calcium atom (Ca) because a calcium ion has:

1. Less electrons
2. Less protons
3. More electrons
4. More neutrons