Chemistry 2016 Jamb Examination
Chemistry 2016 Jamb Examination
Question 31
The number of electronic shells contained in an atom with electron configuration 1S2 2S2 2P6 3S2 3P6 4S2 is
Each principal quantum number (1, 2, 3, 4) represents an electronic shell. The configuration shows electrons in shells 1 to 4, indicating four shells in total.
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Question 32
The drying agent suitable for drying ammonia is
Ammonia is a basic gas, and acidic drying agents such as concentrated \(\text{H}_2\text{SO}_4\) or \(\text{P}_4\text{O}_{10}\) react with it. Calcium oxide is suitable as it is basic and does not react with ammonia.
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Question 33
The arrangement of particles in crystal lattices can be studied using
X-rays have wavelengths comparable to interatomic distances in crystals, making them suitable for studying crystal structures through X-ray diffraction.
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Question 34
In the extraction of iron, the waste gas from the furnace is a mixture of
The blast furnace uses hot air (containing \(\text{N}_2\)) and coke, producing waste gases \(\text{CO}_2\), \(\text{CO}\), and \(\text{N}_2\).
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Question 35
In a neutralization reaction involving HCl and NaOH using litmus as indicator, the colour at the end point is
At the equivalence point of a strong acid and strong base, the solution is neutral (pH ≈ 7). Litmus turns purple in neutral solution.
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Question 36
An example of a solid emulsion is
Butter is a solid emulsion in which water droplets are dispersed in solid fat.
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Question 37
An isotope has an atomic number of 15 and a mass number of 31. The number of proton it contains is
The atomic number equals the number of protons. Hence, the isotope with atomic number 15 contains 15 protons.
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Question 38
Calculate the volume in cm3 of oxygen evolved at s.t.p when a current of 5A is passed through acidified water for 193s. [F = 96500 C mol-1, Molar volume of a gas at s.t.p = 22.4dm3]
From electrolysis of water: \[ 2H_2O \rightarrow 2H_2 + O_2 \] 4 moles of electrons produce 1 mole of \(O_2\). Charge passed, \(Q = It = 5 \times 193 = 965\,C\) \[ \text{Moles of electrons} = \dfrac{Q}{F} \]\[= \dfrac{965}{96500} = 0.01 \] \[ \text{Moles of } O_2 = \dfrac{0.01}{4} = 0.0025 \] \[ \text{Volume at s.t.p} = 0.0025 \times 22.4 \]\[ = 0.056\,dm^3 = 56\,cm^3 \] Hence, the correct volume is 0.056dm³.
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Question 39
The gas that is used for the treatment of cancer is
Radon is a radioactive noble gas used in radiotherapy for treating cancer due to its ability to emit ionizing radiation.
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Question 40
A chemical reaction in which the hydration energy is greater than the lattice energy is referred to as
When hydration energy exceeds lattice energy, excess energy is released to the surroundings. Thus, the reaction is exothermic.
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