THE UNITED REPUBLIC OF TANZANIA
PRESIDENT’S OFFICE, LOCAL GOVERNMENT AND REGIONS ADMISTRATION
FORM SIX ROAD TO NECTA LINDI REGIONS APRIL 2025
132/1 CHEMISTRY 1
TIME: 2.30 HOURS Saturday, 26 April, 2025 am
_______________________________________________________________________________________
INSTRUCTIONS
1. This paper consists of Ten (10) questions in sections A, and B.
2. Answer All questions in Section A and any two (2) questions from section B.
3. Each question in section A carry Ten (10) Marks and each question in section B carries
Fifteen (15) Marks.
4. Mathematical tables and non-programmable calculators may be used.
5. Cellular phones are not allowed in the examination room.
6. Write your Examination Number on every page of your answer sheet(s) .
7. For calculations, the following constants may be used:
Gas constant, R = 8.314Jmol-1 K-1
GMV = 22.4dm3.
Rydberg’s constant, Rh = 1.097 x 107m-1
Velocity of light, C = 3 x 108ms-1
Mass of electron (Me) =9.1 x 10-31kg.
Planck’s constant, h= 6.63x 10-34Js
Atomic masses: H = 1, C = 12, O = 16, N = 14, S = 32, Na = 23, P = 31, Cl = 35.5, Na =23, K = 39,
Br = 80, Cu = 64, Mg = 24, Sr =88.
This paper contains 4 printed pages
Page 1 of 4
SECTION A (70 Marks)
Answer all questions from this section
1. (a) State the following laws:
(i) Hund’s rule (ii) Pauli’s exclusion principle (iii) Aufbau principle
(iv) Heisenberg’s principle of uncertainty (04 Marks)
(b) Explain the main postulates of Bohr’s atomic theory and the shorticoming of Bohr’s atomic theory.
(06 Marks)
2. (a) State Hess’s law (01 Mark)
(b) Explain the meaning of lattice energy. (01 mark)
(c) Given the data below:
(i) Find the enthalpy of formation of MgCl2.
(ii) Draw the Born Haber cycle for MgCl2.
Process kJmol-1
1st I.E of metal +740
2nd I.E of metal +1500
Atomization energy of metal +149
Electron affinity of non-metal -364
Atomization energy of non-metal +121
Lattice energy -2489
(05 Marks)
(d) When 12g of each carbon, hydrogen and ethyl ethanoate are burned completely in oxygen, the quantities
of heat given are respectively 394.2kJ, 1715kJ, and 306kJ. Calculate the enthalpy of formation of ethyl
etahoate. (03 Marks)
3. (a) Define the following:
(i) Hydrogen bond (ii) Coordinate bond
(iii) Polar covalent bond (iv) Metallic bond (02 Marks)
(b) Explain the following facts:
(i) is soluble in water but is insoluble in water.
(ii) Although contains single bonds and double bond, the research show that
all bonds have equal bond length.
(iii) Sodium is very soft and can be cut with knife, on the other hand Magnesium is very
Hard.
(iv) H2O has molar mass of 18g and H2S has molar mass of 34g are hydride of group VI
H2S with large mass has low boiling point than H2O with small molar mass. (08 Marks)
4. (a) (i) Explain three (3) applications of colligative property.
(ii) Show that for very dilute solutions, molality ≈ Molarity.
(iii) Why when a non-volatile and non-electrolyte solute is dissolved in water the
boiling point of water is elevated? (03½ Marks)
Page 2 of 4
(b) (i) The sugar fructose contains 40.0% C, 6.7% H, and 53.3% O by mass. A solution of
11.7 g of fructose in 325 g of ethanol has a boiling point of 78.59 °C. The boiling point
of ethanol is 78.35 °C, and Kb for ethanol is 1.20 °C/m. What is the molecular formula
of fructose?
(ii) Arrange the following solutions in order by their decreasing freezing points:
0.1 mNa3PO4, 0.1 m C2H5OH, 0.01 m CO2, 0.15 m NaCl, and 0.2 m CaCl2. (03 Marks)
(c) An aqueous sucrose solution of unknown concentration is found to have a freezing point
of -0.912ºC. What is the normal boiling point and the partial pressure (in torr) of water
at 25ºC of this solution. Sucrose is a non-volatile, non-electrolyte.
(Po (H2O) = 23.8 mmHg at 25oC) (03½ Marks)
5. (a) Define the following:
(i) Heterogenous equilibrium (ii) Reaction quotient
(iii) Equilibrium mixture (iv) Reversible reaction (02 Marks)
(b) Give three (3) differences between equilibrium reaction and reversible reaction (03 Marks)
(c) Nitrogen and oxygen combine endothermically at elevated temperature according to equation:
If the equilibrium constant for the reaction is 4.3 x 103 at 30000C and 1 atm, Calculate the
composition of each in equilibrium if 2 moles of each nitrogen and oxygen were heated. (05 Marks)
6. (a) Give the IUPAc name of the following organic compounds:
(04 Marks)
(b) 10cm3 of unknown hydrocarbon Q combusted with 150cm3 of excess oxygen. After
combustion and cooling 120cm3 of the gas was produced. The produced gas reduced to 60cm3
when passed through KOH. Identify molecular formular of hydrocarbon Q. Then give two
possible structures of Q. (06 Marks)
7. (a) Define the following terms:
(i) Ideal gas (ii) Real gas (iii) Critical temperature
(iv) Compressibility factor (v) Root Mean Square speed (vi) Partial pressure (03 Marks)
(b) 100cm3 of a gas containing mixture of CO2 and O2 used 12 seconds to effuse through the orifice and
the same volume of gas Q used 10 seconds to effuse through the same orifice.
(i) Calculate the molar mass of gas Q if the mixture of CO2 and O2 has molar mass of 40.3g/mole
(ii) Calculate the percentage composition of CO2 and O2 in the mixture.
(iii) Identify the gas Q (04½ Marks)
Page 3 of 4
(c) ) Dinitrogen Tetraoxide decomposes to form Nitrogen Dioxide in the reaction N2O4 2NO2.
2 atm of dinitrogen tetraoxide is added to a 500 mL container at 273 K. After several minutes, the
total pressure of N2O4 and 2NO2 at equilibrium is found to be 3.2 atm. Find the partial pressures of
both gases. (02½ Marks)
SECTION B (30 Marks)
Answer only two (2) questions from this section
8. (a) Explain the following with the aid of chemical reactions:
(i) Preparation of metallic hydroxides by direct method.
(ii) Preparation of metallic hydroxides by indirect method.
(iii) Heating MgCl2.6H2O does not give anhydrous MgCl2.
(iv) Iron (III) carbonate cannot be prepared. (08 Marks)
(b) By giving chemical reactions describe the meaning of the following terms:
(i) Zinc Oxide is amphoteric.
(ii) Calcium oxide is basic in nature. (04 Marks)
(c) By giving examples state the three (3) uses of metallic sulphates in real life. (03 Marks)
9. (a) Explain three (3) sources and three (3) effects of soil acidity. (06 Marks)
(b) Give three (3) advantage of Manure over Fertilizer. (03 Marks)
(c) If one hectare need 2000Kg of Nitrogen. What Kg of urea is needed if the urea fertilizer has analysis of
46-0-0. (02 Marks)
3
(d) 10g of oven dry soil was dissolved by 60cm of 0.1M NaOH solution, then the excess base required
20cm3 of 0.2M HCl for neutralization. If the Percentage Base Saturation of the soil is 75%, calculate
the Cation Exchange Capacity (C.E.C) of the soil. (04 Marks)
10. (a) (i) By using the chemical equation explain why tertiary haloalkane can not undergo SN2 reaction.
(ii) Benzene is more reactive than Nitrobenzene while Methylbenzene is more reactive than benzene.
Explain this observation. (04 Marks)
(b) From the reaction scheme below identify the molecules V, W, X, Y and Z:
(03 Marks)
(c) Convert the following organic compounds using not more than five steps:
(i) CH3CH2CH3 to Phenol
(ii) CH3CH2OH to Benzene (08 Marks)
Page 4 of 4
