Chemistry Exam Past Questions and Answers | JAMB, WAEC and NECO

Chemistry is the study of the substances that make up matter. It looks at their properties, how they react with each other, and how these reactions can create new substances.

• Question 1371:

  A solution X, on mixing with AgNO${}_3$ solution gives a white precipitate soluble in aqueous NH${}_3$, a solution Y, when also added to X, also gives a white precipitate which is soluble when heated solutions X and Y respectively contain

  Options:
  A) Al${}^{3+}$, Cl${}^{-}$
  B) Hg${}^{+}$, SO${}_4^{2-}$
  C) Pb${}^{2+}$, Cl${}^{-}$
  D) Ag${}^{+}$, SO${}_4^{2-}$
  Show Answer
  The correct answer is C .
• Question 1372: Chlorine, bromine and iodine resemble each other in that all? Options:
  A) dissolve in alkalis
  B) react violently with hydrogen without heating
  C) displace each other from solutions of their salts
  D) are gases
  E) are liquids
  Show Answer
  The correct answer is A .
• Question 1373:

  

  The diagram shown above represents the solubility curves of two salts, X and Y, in water, use this diagram to answer the question. If the molar mass of X is 36 g, the number of moles of X dissolved at 343 K is

  Options:
  A) 0.2 moles
  B) 0.7 moles
  C) 1.5 moles
  D) 2.0 moles
  E) 3.0 moles
  Show Answer
  The correct answer is B .
• Question 1374:

  2Cl_2(g) + 2H₂O_(g) 4HCl_(g) + O_2(g)

  ∆H° = +115KJ mol^-1. In the above equilibrium reaction, a decrease in temperature will?

  Options:
  A) favour the reverse reaction
  B) favour the forward reaction
  C) have no effect on the equilibrium state
  D) double the rate of the reverse raection
  Show Answer
  The correct answer is A .
• Question 1375: Which of these metals, Mg, Fe, Pb and Cu will dissolve in dilute HCI? Options:
  A) All the metals
  B) Mg ,Fe and Cu
  C) Mg, Fe and Pb
  D) Mg and Fe only
  E) Mg only
  Show Answer
  The correct answer is D .
• Question 1376: When a pressure cooker is half filled with water, and heated to boiling point, then the pressure inside the cooker will? Options:
  A) decrease, since only a fraction of the water molecules has changed to vapour
  B) remain constant, because the total number of water molecules has not changed
  C) increase, because the water molecules can now reach every part of the sealed tube
  D) decrease, since water boils under reduced pressure
  E) increase, because the water vapour molecules now strike the walls of the tube more frequently because of their increased velocity
  Show Answer
  The correct answer is E .
• Question 1377: A blue solid, T, which weighed 5.0g was placed on a table. After 8 hours, the resulting pink solid was found to weigh 5.5g. It can be inferred that substance T? Options:
  A) is deliquescent
  B) is hydroscopic
  C) has some molecules of water of crystallization
  D) is efflorescent
  Show Answer
  The correct answer is A .
• Question 1378: Which of the following questions is correct about the periodic table? Options:
  A) The non-metallic properties of the elements tend to decrease across each period
  B) The valence electrons of the elements increase progressively across the period
  C) Elements in the same group have the same numbeer of electron shells
  D) Elements in the same period have the number of valence electrons
  Show Answer
  The correct answer is B .
• Question 1379:

  Na${}_2$CO${}_3$ + 2HCl $\to$ 2NaCl + H${}_2$O + CO${}_2$

  The indicator most suitable for this reaction should have a pH equal to

  Options:
  A) 5
  B) 7
  C) 3
  D) 9
  Show Answer
  The correct answer is C .
• Question 1380: The tincture of iodine means iodine dissolved in Options:
  A) ethanol
  B) bromine chloride
  C) chlorine water
  D) water
  Show Answer
  The correct answer is A .