Chemistry JAMB, WAEC, NECO AND NABTEB Official Past Questions

What would be observed when aqueous ammonia is added in drops and then in excess to a solution of copper(II) ions?

The basic property of salts used as drying agents is by?

What number of moles of oxygen would exert a pressure of 10 atm at 320 K in an 8.2 dm\(^{2}\) cylinder?

[R = 0.082 atm dm\(^{3}\) mol\(^{-1}\) K\(^{-1}\)]

The most common method of preparing insoluble salts is by

A molecular of phosphorus is

Which of the following gasses is highly soluble in water at room temperature

The formation of ethene from dehydration of ethanol can be described as——-

Which of the graphs illustrates the variation of the solubility of a salt in water (y-axis), with an increase in temperature (x-axis) if the dissolution process is exothermic?

Which of the graphs illustrates the variation of the pH of a given volume of strong acid solution (y-axis) with the volume of strong base titrated against its (x-axis)?

Which of the following illustrates the variation of the rate of evolution of gas from a given length of magnesium ribbon (y-axis) with an increase in the concentration of the added (x-axis)?

Which of the following pairs of compounds would form a precipitate when their aqueous solutions are mixed?

The alkanol represented by the structure above is

If humid air is polluted by chlorine discharged, the air can be restored by sprinkling

Cathodic protection of metals is based on

What is the relative molecular mass of the compound below?

[H = 1.0; C = 12.0; O = 16.0]

The ratio of carbon atoms of hydrogen atoms in a hydrocarbon is 1:2. If its molecular mass is 56, what is its molecular formula?

Which of the following oxide causes acid rain?

The hydrolysis of proteins by diluting mineral acids produces 

Aqueous solutions of zinc chloride, calcium chloride iron (lII) tetraoxosulphate (VI) and lead (II) trioxonitrate (IV) are contained in four separate bottles whose labels have been lost. Using aqueous ammonia solution only, show how you would identify the content of each bottle.

Carry out the following exercises on sample C. Record your observations and identify any gases evolved. State the conclusion you draw from the result of each test.

(a) Put about half of sample C into a conical flask and add about 5cm\(^3\) of tetrachloroethane followed by 15cm\(^3\) of water. Shake vigorously for about one minute. Put the resulting mixture into a burette and allow to stand until two layers separate. Run the two layers into two separate conical flasks and label them accordingly.

(b) Using the following reagents only, bench sodium hydroxide solution, aqueous ammonia solution, aqueous lead (II) trioxonite (V) solution, silver trioxonitrate (V) solution. bench trioxonitrate (V) acid. Identify the ions present in the upper layer solution

(c) Add 2 – 3 drops of the lower layer solution to about 2cm\(^3\) of starch solution from your result, name the substances which dissolved in the upper and lower layers. 

A solution of a mineral acid containing 0.10 mol of the acid per dm of solution. B IS a solution Containing 1.325g of anhydrous sodium trioxocarbonate (IV) per dm of solution.

(a) Put A into the burette and titrate with 20cm\(^3\) or 25cm\(^3\) portions of B using methyl orange as an indicator. Record the volume of your pipette

(b) From your results and the information is given, calculate;

(i) The number of mole of acid in the average titre

(ii) The number of mole of sodium trioxocarbonate (IV) in the volume of B pipette,

(iii) The mole ratio of acid to base in the reaction [H = 1, C = 12, O = 16, Na 23]

(c) Suggest what the acid in (a) Could be giving reasons for your answer. Hence, write the equation for the reaction.