Year :
1979
Title :
Chemistry
Exam :
JAMB Exam
Paper 1 | Objectives
11 - 20 of 49 Questions
| # | Question | Ans |
|---|---|---|
| 11. |
Helium atoms are chemically unreactive because A. there are no electrons around the nucleus B. the number of protons equals the number of electrons C. there are equal number of protons and neutrons in the nucleus D. the outer electron shell is completely filled E. the atoms contain only protons |
D |
| 12. |
\(50cm^{3}\) of hydrogen are sparked with \(20cm^{3}\) of oxygen at \(100°C\) and \(1atm\) . The total volume of the residual gases in A. 50 cm3 B. 10 cm3 C. 40 cm3 D. 30 cm3 E. 70 cm3 Detailed SolutionThe equation of the reaction is:\(2H_{{2}{(g)}} + O_{{2}{(g)}} = 2H_{2}O_{(g)}\) Before Sparking we have : \(50cm^{3} : 20cm^{3}\) On Sparking, \(40cm^{3} : 20cm^{3} : 40cm^{3}\) After Sparking, we have \(10cm^{3} : 0 : 40cm^{3}\) Hence, the volume of residual gases = \((10+40)cm^{3} = 50cm^{3}\) |
|
| 13. |
How many grams of HBr would exactly be required to react with 2 g of propyne? (C =12, H=1, Br = 80) A. 1 g B. 1 g C. 1g D. 16.2g Detailed Solution2HBr + C3H4 \(\to\) C3H6 + 2Br164gms of HBr reacts with 40gms of propyne 2gms of propyne will react with \(\frac{164}{40} \times \frac{2}{1}\) = 8.1gms HBr |
|
| 14. |
When ammonium, potassium and calcium carbonates are each separately heated A. none of them will decompose B. each of them will decompose to give carbondioxide and the respective oxide C. ammonium carbonate and potassium carbonate will not decompose D. only ammonium carbonate and the respective oxide E. ammonium carbonate will decompose to give carbondioxide, water and ammonia Detailed SolutionSolid ammonium carbonate decomposes as it is heated.(NH4)2CO3 → 2 NH3 + CO2 + H2O |
|
| 15. |
If chlorine gas is bubbled into water and then this yellowish-green coloured solution is exposed to bright sunlight for a while A. the solution will give out chlorine gas and hydrogen chloried gas B. the solution will produce chlorine gas and oxygen C. the solution will give out solution will producing hypochloric acid D. the solution is decomposed giving out oxygen, hydrogen and chlorine E. the solution will give out oxygen gas leaving behind aqueous hydrochloric acid |
E |
| 16. |
12 g of solid protassium chlorate (KCIO) were added to 40 g of water and heated to dissolve all the solid. As the solution cools, crystals of potassium chlorate at 66 oC. The solubility of potassium chlorate at 66 oC is therefore A. 66 B. 33 C. 10 D. 20 E. 30 Detailed SolutionThe solubility of KClO3 at 66oC will be \(\frac{12}{40} \times \frac{100}{1}\)= 30 |
|
| 17. |
In the electrolysis of dilute sulphuric acid using platinum electrodes, the products obtained at the anode and cathode are: A. Sulphur hydrogen B. Hydrogen oxygen C. Oxygen Hydrogen D. Hydrogen sulphate ions E. Sulphur oxygen |
C |
| 18. |
The empirical formula of an oxide of nitrogen containing 30.4 per cent of nitrogen is (N=14.0,O=16.0) A. N2O2 B. NO C. NO2 D. N2O E. N2O3 |
C |
| 19. |
When a piece of charcoal enclosed in a cylinder containing air is ignited A. the toatl volume of air is increased B. the relative amount of oxygen present is increased C. the relative amount of nitrogen present is decreased D. the relative amount of carbondioxide present is increased E. the ratio of oxygen to nitrogen in the system is increased |
D |
| 20. |
Indicate which of the following statements is not true as we move from left to right along the periodic Table: A. atomic number of elements increases B. atomic mass of elements increases C. electropositive character of elements increases D. electronegative character of elements increases E. number of electrons in the outermost orbits of element increases |
C |
| 11. |
Helium atoms are chemically unreactive because A. there are no electrons around the nucleus B. the number of protons equals the number of electrons C. there are equal number of protons and neutrons in the nucleus D. the outer electron shell is completely filled E. the atoms contain only protons |
D |
| 12. |
\(50cm^{3}\) of hydrogen are sparked with \(20cm^{3}\) of oxygen at \(100°C\) and \(1atm\) . The total volume of the residual gases in A. 50 cm3 B. 10 cm3 C. 40 cm3 D. 30 cm3 E. 70 cm3 Detailed SolutionThe equation of the reaction is:\(2H_{{2}{(g)}} + O_{{2}{(g)}} = 2H_{2}O_{(g)}\) Before Sparking we have : \(50cm^{3} : 20cm^{3}\) On Sparking, \(40cm^{3} : 20cm^{3} : 40cm^{3}\) After Sparking, we have \(10cm^{3} : 0 : 40cm^{3}\) Hence, the volume of residual gases = \((10+40)cm^{3} = 50cm^{3}\) |
|
| 13. |
How many grams of HBr would exactly be required to react with 2 g of propyne? (C =12, H=1, Br = 80) A. 1 g B. 1 g C. 1g D. 16.2g Detailed Solution2HBr + C3H4 \(\to\) C3H6 + 2Br164gms of HBr reacts with 40gms of propyne 2gms of propyne will react with \(\frac{164}{40} \times \frac{2}{1}\) = 8.1gms HBr |
|
| 14. |
When ammonium, potassium and calcium carbonates are each separately heated A. none of them will decompose B. each of them will decompose to give carbondioxide and the respective oxide C. ammonium carbonate and potassium carbonate will not decompose D. only ammonium carbonate and the respective oxide E. ammonium carbonate will decompose to give carbondioxide, water and ammonia Detailed SolutionSolid ammonium carbonate decomposes as it is heated.(NH4)2CO3 → 2 NH3 + CO2 + H2O |
|
| 15. |
If chlorine gas is bubbled into water and then this yellowish-green coloured solution is exposed to bright sunlight for a while A. the solution will give out chlorine gas and hydrogen chloried gas B. the solution will produce chlorine gas and oxygen C. the solution will give out solution will producing hypochloric acid D. the solution is decomposed giving out oxygen, hydrogen and chlorine E. the solution will give out oxygen gas leaving behind aqueous hydrochloric acid |
E |
| 16. |
12 g of solid protassium chlorate (KCIO) were added to 40 g of water and heated to dissolve all the solid. As the solution cools, crystals of potassium chlorate at 66 oC. The solubility of potassium chlorate at 66 oC is therefore A. 66 B. 33 C. 10 D. 20 E. 30 Detailed SolutionThe solubility of KClO3 at 66oC will be \(\frac{12}{40} \times \frac{100}{1}\)= 30 |
|
| 17. |
In the electrolysis of dilute sulphuric acid using platinum electrodes, the products obtained at the anode and cathode are: A. Sulphur hydrogen B. Hydrogen oxygen C. Oxygen Hydrogen D. Hydrogen sulphate ions E. Sulphur oxygen |
C |
| 18. |
The empirical formula of an oxide of nitrogen containing 30.4 per cent of nitrogen is (N=14.0,O=16.0) A. N2O2 B. NO C. NO2 D. N2O E. N2O3 |
C |
| 19. |
When a piece of charcoal enclosed in a cylinder containing air is ignited A. the toatl volume of air is increased B. the relative amount of oxygen present is increased C. the relative amount of nitrogen present is decreased D. the relative amount of carbondioxide present is increased E. the ratio of oxygen to nitrogen in the system is increased |
D |
| 20. |
Indicate which of the following statements is not true as we move from left to right along the periodic Table: A. atomic number of elements increases B. atomic mass of elements increases C. electropositive character of elements increases D. electronegative character of elements increases E. number of electrons in the outermost orbits of element increases |
C |