Jamb Chemistry Past Questions And Answers
Chemistry explores the substances of which matter is composed, the investigation of their properties and reactions, and the use of such reactions to form new substances. This subject is popular among science students.
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You are welcome to 2021 JAMB Chemistry questions and answers. Before we move to Jamb Chemistry question and answer, it is important you know the tricks and what JAMB sets in Chemistry that would help you score high in your Jamb Chemistry examination.
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Tricks to answer Jamb Chemistry Questions
Knowing some constants like mass and the atomic number of elements in chemistry, Avogadro’s number, the mass of the proton, neutron and electron, speed of light e.t.c will help you to answer some bonus questions asked by Jamb without giving some constants.
It is also important to note some popular principles and laws in chemistry as most of them would form part of the question you will see in your Jamb Chemistry questions.
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Jamb Chemistry Past Questions And Answers
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1. What is the shape of a molecule of CCl4?
C. Trigonal planar
ANSWER: B (Tetrahedral)
2. A sample of gas with an initial volume of 2.5 dm3 is heated and then allowed to expand to 7.5 dm3 at constant at pressure. What is the ratio of the final temperature of the initial absolute temperature?
ANSWER: A (3:1)
3. 6g of Mg was to 100cm3 of 1 moldm3 H2 SO4 . What mass of Mg remained undissolved? (Mg = 24)
ANSWER: C (3.6)
4. Which of the following will act as both oxidizing agents and reducing agents?
A. H2 S
ANSWER: D ( SO2 )
5. A metal which can be used as sacrificial anode for preventing corrosion of length of iron pipe is
ANSWER: C (Silver)
6. Which of the following increases as boiling water changes to steam?
A. Temperature of the system
B. degree of disorder of the system
C. number of molecule
D. Activation energy
ANSWER: B (Degree of disorder of the system)
7. Which of the following is stable to heat
B. ( NH4 )2 SO4
C. Ag NH3
D. K2 CO3
ANSWER: D ( K2 CO3 )
8. Which of the following will precipitate in dil. HCl
B. Na2 S
C. Fe S
ANSWER: D ( CuS )
9. Which of the following does NOT contain aluminum as a component?
A. Over-head cables
C. Container for caustic soda
D. Container for trioxonitrate (v) acid
ANSWER: C (Container for caustic soda)
10. The removal of rust from iron by treatment with tetraoxosulphate (vi) acid is based on the
A. Hydrolysis of the iron
B. Reaction of acid with base
C. Oxidation of the rust
D. Dehydration of the iron
ANSWER: D ( Dehydration of the iron )
11. Which of the following constitutes a mixture? I. Petroleum II. Rubber latex III. Vulcanizer’s solution IV. Carbon (iv) sulphide
A. I, II and III
B. I, II and IV
C. I and II only
D. I and IV
ANSWER: A ( I, II and III)
12. 30 cm3 of oxygen at 10 atmosphere pressure is placed in a 20 dm3 container. Calculate the new pressure if the temperature is kept constant.
A. 6.7 atm
B. 15.0 atm
C. 6.0 atm
D. 66.0 atm
ANSWER: A ( 15.0 atm)
13. A sample of gas exerts a pressure of 8.2 atm when confined in a 2.93 dm3 container at 20c. The number of moles of gas in the sample is
A. 1. 00
ANSWER: A ( 1.00)
14. A quantity of air passed through a weighted amount of alkaline pyrogallol. An increase in the weight of the pyrogallol would result from the absorption of
ANSWER: D ( Oxygen)
15. There is a large temperature interval between the melting point and the boiling point of metal because:
A. metals have a very high melting point
B. metals conduct heat very rapidly
C. melting does not break the metallic bond but boiling does
D. the crystal lattice of metal is easily broken
ANSWER: A ( metals have very high melting point)
16. Copper (II) tetraoxosulphate (IV) is widely used as
ANSWER: B ( fungicide)
17. Which of the following substances is not a homogeneous mixture?
A. filtered sea water
B. soft drinks
C. flood water
D. writing ink
ANSWER: C ( floodwater)
18. Ethene, when passed into concentrated H2SO4, is rapidly absorbed. The product is diluted with water and then warmed to produce
B. diethyl ether
D. diethyl sulphate
ANSWER: A ( Ethanol)
19. A certain liquid has a high boiling point. It is viscous, non-toxic, and miscible with water to be hygroscopic; this liquid most likely to be
ANSWER: D (CH3OHCHOH2OH)
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20. Which of the following statement is TRUE of the complete hydrolysis of a glyceride by sodium hydroxide?
A. 3 moles of NaOH are required for each mole of glyceride
B. 3 moles of glycerol are produced
C. only one mole of soap is formed
D. concentrated H2SO4 is essential for the completion of the reaction.
ANSWER: A (3 moles of NaOH are required for each mole of glyceride)
21. A piece of radioactive element has initially 8.0×10^22 atoms. The half life of two days after 16 days the number of atom is
ANSWER: B (5×10^21)
22. Chlorine is a common bleaching agent. This is not true with
A. wet litmus paper
B. printers ink
C. wet pawpaw leaf
D. most wet fabric dyes
ANSWER: B (printers ink)
23. Calcium forms complexes with ammonia because
A. it is a transition metal
B. it is an s-block element
C. it has empty d-orbital
D. it forms colourless compounds
ANSWER: C (it has empty d-orbital)
24. The IUPAC name for CICH2-CH2-CH2-OH is
C. 1 cholorpropano
ANSWER: B (3-choropropan-1-ol)
25. An organic compound decolourized acidified KMnO4 solution but failed to react with ammonical AgNO3 solution. The organic compound is likely?
A. a carboxylic acid
ANSWER: D (Alkyne)
26. A certain volume of gas at 298k is heated such that its volume and pressure are now four times the original values. What is the new temperature?
ANSWER: D (4768.0K)
27. The boiling point of water, ethanol, toulene and butan-2-ol are 373.0k, 351.3k, 383.6k and 372.5k respectively, which liquid has the highest vapour pressure at 323.0k
ANSWER: C (ethanol)
28. The function of sulphur during the vulcanization of rubber is to
A. act as a catalyst for the polymerization of rubber molecules
B. convert rubber from thermosetting to thermoplastic polymer
C. form chains which bind rubber molecules together
D. break down rubber polymer molecules
ANSWER: C (form chains which bind molecules together)
29. Complete dehydrogenation of ethyne yields
ANSWER: D (propane)
30. Mixing aqueos solution of barium hydroxide and sodium tetraoxocarbonate (iv) yields a white precipitate of
A. Barium oxide
B. Sodium tetraoxocarbonate
C. Sodium hydroxide
D. Barium tetraoxocarbonate
ANSWER: D (Barium tetraoxocarbonate)
31. Which of the following conducts electricity?
D. Red phosphorous
ANSWER: B (graphite)
32. Which of the following compound is NOT the correct formed compound when the parent metal is heated in air?
A. Calcium oxide
B. Sodium oxide ( Na2O )
C. Copper (II) oxide (CuO)
D. tri-iron tetraoxide (Fe2O)
ANSWER: D (tri-iron tetraoxide (Fe2O))
33. When marble is heated to 1473K, another whiter solid is obtained which reacts vigoriously with water to give an alkaline solution. The solution contains
ANSWER: D ( Ca(OH)2 )
34. Which of the following roles does sodium chloride play in preparation? It
A. reacts with glycerol
B. purifies the soap, accelerates the decomposition of fat and oil
C. separates soap from glycerol
D. converts the fat acid to its sodium salt
ANSWER: C ( separates soap from glycerol )
35. Which of the following is used as a moderator to control nuclear fission?
B. Heavy water
ANSWER: B ( heavy water)
36. One of the active components of baking powder is
ANSWER: B ( NaHCO3 )
37. H2SO4 is used to remove rust on the surface of iron (picking) before electroplating. The type of reaction involved is
A. redox reaction
C. Double decomposition
ANSWER: A ( redox reaction)
38. Silver chloride turns gray when exposed to sunlight because
A. the silver ion is reduced to silver
B. the silver io is oxidized to silver
C. silver is transition metal
D. the silver chloride forms complexes in the sun
ANSWER: C ( silver is transition metal)
39. which of these compounds exhibits resonance
ANSWER: A ( Benzene)
40. The oxidation number of oxygen in BaO2 is
ANSWER: C ( redox reaction)