Jamb 2019 CHEMISTRY likely exam questions & answers

1. A mixture of solutions of barium chloride and sodium trioxocarbonate IV yield a white precipitate A) Soluble in ammonia B) soluble in dilute hydrochloric acid C) soluble in alkali  D) soluble in dilute tetraoxosulphate VI acid
Right choiceOption B

2. Four solutions P, Q, R, and S contain chloride, sulphide, tetraoxosulphate VI and trioxocarbonate IV respectively. One reagent that will identify only one of them completely by a precipitation reaction is  A) Potassium hydroxide solution B) Dilute tetraoxosulphate(VI) acid  C) Dilute trioxonitrate (V) acid  D) ead trioxonitrate (V) solution
Right choiceOption D

3. Which of the following is true of alkalis A)  They have a sour taste B)  They liberate ammonia when added to ammonium chloride C) Their pH is 7 D) They turn phenolphthalein colourless
Right choiceOption A

4. Real gases do not obey the ideal gas laws at  A) High temperature  B) Low temperature and high pressures  C) Low pressures D) High temperatures and pressures
Right choiceOption A

5. A 3.0 g mixture of sodium trioxocarbonate (IV) and calcium trioxocarbonate (IV) liberated 0.44 g of carbon IV oxide on strong heating until no more gas was evolved. What is the percentage of sodium trioxocarbonate IV in the mixture? [ Ca = 40, C=12, O= 16, Na = 231 A) 67  B) 23 C) 76 D)32
Right choiceOption A

6. Which of the following planets contains a large amount of solid methane?  A) Jupiter B) Neptune  C) Pluto D) Saturn Right choiceOption C

7. What change will occur during the electrolysis of brine using carbon electrodes? A) Chlorine will be given off at the cathode B) Oxygen gas will be given off at the anode C) Sodium will be deposited at the cathode D) The volumes of hydrogen and chlorine given off at the same time are equal
Right choiceOption D

8. Nuclear reactions can be used in the following except A) gauging the thickness of objects B) making atomic bombs C) curing cancer D) purifying water Right choiceOption D

9. Which of the following is a good conductor of electric current? A)  Mixture of petrol and kerosene B) Aqueous solution of sugar C) Mixture of ethanol and water D) Aqueous solution of table salt Right choiceOption D

10. The pH value o fan aqueous solution of compounds remains at 5 even when contaminated with small quantities of acid or alkali. Which one of the following pairs of compounds would produce such a solution? A) Ammonia and ammonium chloride  B) Ethanoic acid and sodium C) ethanoate  Hydrochloric acid and sodium chloride D) Potassium hydroxide and potassium bromide
Right choiceOption A or B

11. A sample of orange juice has pH of 3.80. What is the molar concentration of hydrogen ion in the juice? (a) 1.588 x 104(b) 1.58 x 10-4 (c) 1.58 x 103 (d) 1.58 x 104  Right choice – Option D

12. Which of the following solutions is NOT acidic? (a) Aluminium chloride (b)Zinc chloride (c) Copper (II) tetraoxosulphate (VI) (d) Silver chloride Right choice – Option

13. Calculate the current in ampere required to produce 8.0g of aluminium in 1.50 hours (Al = 27, F = 96500C) (a) 33.65 A (b) 35.74A (c) 37.85 A (d) 39.25 A Right choice – Option B

14. Calculate the oxidation number of chlorine in Cl2O2 (a) +1 (b) +2 (c) +5 (d) +1 Right choice – Option B

15. The two nuclei in the hydrogen molecule are held together by (a) mutual attraction (b) mutual sharing of the electron charge (c) dative covalent bond (d) the two electrons having the same spin Right choice – Option B

16. Which of the following statements about catalysis is correct? (a) A smaii amount of cataiyst often affects the rate of a reaction lbr a long time (b) A catalyst is always chemically unchanged at the end of a
reaction (c) The effect of a catalyst is often enhanced by adding promoters ()d A catalyst always physically unchanged at the end of a reaction (e) A cataiyst ahvays speeds up the rate of a chemical reaction
(a) a,b,c,d,e (b) a,b,c only (c) a,b,d only (d) b,d only Right choice – Option A

17. When K2Cr2O7 dissolves in water, the following equilibrium is established Cr2O72-(aq) + H2O(l)  —> 2CrO42-(aq) + 2H+(aq) Orange yellow State the colour observed on adding a few drops of dilute H2SO4 in the system (a) orange (b) yellow (c) pink (d) colourless Right choice – Option A

18. Which of the lbllowing statements is NOT true of hydrogen sulphide? (a) it is a liquid at temperature (b) it is a covalent compound (c) it is weak dibasic acid in aqueous solution (d) it is a much stronger reducing agent than water Right choice – Option A

19. Which of the following are products of acid hydrolysis of sucrose? (a) fructose and maltose (b) glucose and cellulose (c) maltose and cellulose (d) glucose and fructose Right choice – Option D

20. What is the concentration (in mol./dm3) of a solution containing 0.38g of potassium hydroxide 100cm3 of solution? (K= 39, H = 1, O = 16 (a) 0.028 (b) 0.04 (c) 0.05 (d) 0.07 Right choice – Option D

21. Trichloromethane is a solvent used to remove grease from clothing. How after use is the solvent separated from the
grease? (a) by chromatography (b) by crystallization d) by distillation d)by filtration Right choice – Option C

22. Arrange the following elements of the second period in the order of increasing atomic radius : lithium, beryllium, boron, carbon
(a) carbon, boron, beryllium, lithium (b) lithium, beryllium, boron, carbon (c) lithium, carbon, boron, beryllium
(d) carbon, lithium, beryllium, boron Right choice – Option B

23. Argon is used in gas filled electric lamps because (a) it is radioactive (b) it has low pressure (c) is combustible (d) it heips to prevent oxidation Right choice – Option D

 

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