SS 3 CHEMISTRY PAST QUESTIONS (WAEC/NECO)

The spontaneity of a chemical reaction is determined by the change in the

Which of the following features of a human skeleton can be determined by carbon-dating?

Electrovalent compounds are characterized by

An exothermic reaction is one which involves

What is the oxidation number of nitrogen in AI(NO₃)₃?

What mass of copper would be deposited by a current of 1. 0 ampere passing for 965 seconds through copper (ll) tetraoxosulphate (IV) solution? [Cu = 63.5; 1F = 96500C]

Which of the following will produce oxygen and hydrogen during its electrolysis using platinum electrode?

Which of the following substances decomposes when an electric current is passed through it?

A mixture of calcium chloride and calcium trioxocarbonate (IV) in water can be separated by

Two radioactive elements Q and S have half-life periods of 10 hours and 20 hours respectively. Therefore

Helium is preferred to hydrogen in filling balloons because hydrogen

A radioactive solid is best stored

Metals are said to be malleable because they

If an element with high electron affinity combines with another element with low ionization energy the bond formed will be mainly

A reaction is represented by the equation below. A_2(g) + B_2(g) 2AB_(g); ∆H = +X kJmol^-1 Which of the following statements about the system is correct?

Rusting of iron is an example of

If the solubility of KHCO₃ is 0.40 mole dm^-3

Which of the following procedures is suitable for identifying the food colouring added to a pastry sample?

What will be the effect of increase in pressure on the following system at equilibrium? 2NH_2(g) N_2(g) + 3H_2(g)

Aluminium is extracted from

Which of the following non-metals reacts most readily with metals?

The presence of unpaired electrons in an atom of a transition metal gives rise to

Which of the following compounds dissolves in water to give an alkaline solution?

Which of the following contains co-ordinate covalent bond?

One mole of a compound M(HCO₃)₂ has a mass of 162g. Calculate the relative atomic mass of M. [H = 1, C =12, O = 16]

A concentrated solution containing H⁺, Cu²⁺,OH^- and CI^- was electrolysed using platiunm electrodes which of the ions will be discharged at the cathods?

A sheet of paper is placed in the path of a beam from a radioactive source. The emissions that pass through the paper consist of

Elements which belong to the same group in the Periodic Table are characterized by

What is oxidized in the reaction represented by the following equation? 3CU + 8HNO₃ → 3Cu(NO₃)₂ + 2NO + 4H₂O

It can be concluded that gastric juice

P _Total = F₁ + P₂ + P ₃ + .........P_n' where P _Total is the pressure of a mixture of gasses. The equation above is an expression of

Which of the following increases as boiling water changes to steam?

Which of the following occurs when a solution of CuSO₄ is electrolysed using copper electrodes?

Dehydration of ethanol produces

What is the function of sulphur (IV) oxide in the reaction represented by the following equation? SO _2(aq) + 2H₂S_(g) → 3S _(s) + 2H ₂O _(l)

The atoms of four elements are represented as ₂₀Q, ₁₆R, ₁₀S and ₈T Which of the elements would be unreactive?

The type of chemical bond that exists between potassium and oxygen in potassium oxide is

0.10 mol dm^-3 NaCI conducts electricity better than 0.10 mol dm^-3 CH₃COOH because the solution of NaCI

The liquid product of the destructive distillation of coal is

Which of the following lowers the activation energy of a chemical reaction?

Which of the following properties increases down a group in the Periodic Table?

What type of reaction is involved when wood shavings produce a brown gas with concentrated HNO₃?

What is responsible for metallic bonding?

Equal volumes of CO₂ cnd CO at s.t.p have the same

The property of calcium chloride which makes it useful as a drying agent is that it is

Which of the following will displace copper from a solution of copper (ll) salt?

Which of the following statements about ideal gases is/are correct?

I. The cohesive forces between their particles are negligible

ll. The have no definite volume but occupy the volume of their containers

III. They are not compressible

IV. Their particles collide with loss of energy

Which of the following can undergo both addition reactions and substitution reactions?

Calcium atom ionizes by

Which of the following would dissolve in warm dilute H₂SO₄ without effervescence, to give a blue solution?

Substances which absorb water from the atmosphere without dissolving in it are said to be

Which of the following compounds dissolves in water to form a solution with pH below 7?

A finely divided from of a metal burns more readily in air than the rod from because the rod has

Which of the following pairs of reagents recat to produce hydrogen?

Petrol consists mainly of

Given that the order of reactivity of four metals is P>Q>R>S, which of the following reactions is feasible?

What is the value of x in the following equation? Cr₂O₇^2- + 14H⁺ + xe- → 2Cr³⁺ + 7H₂O

Pauli Exclusion Principle is related to

What is the shape of a molecule of CCI₄?

Which of the following movements can be described as random motion?

What does ∆H represent in the following equation ? Cl_(g) + e- → CI- _(g); ∆H = - 363 kJ mol-¹

When alkanols react with sodium, the ga evolved is

Exhaust fumes discharged from a smoky vehicle gradually become invisible as a result of

The crystal layers in graphite are held together by

Chlorine atom forms CI by

Chemical equilibrium is attained when

What volume of hydrogen is produced at s.t.p. When 2.60 g of zinc reacts with excess HCI according to the following equation? Zn_(s) + 2HCI_(aq) → ZnCI _2(aq) + H_2(g) [Zn = 65; 1 mole of a gas occupies 22.4dm³ at s.t.p]

What is the effect of using vanadium (V) oxide as catalyst in the reaction represented by the following equation? 2SO₂ + O₂ ⇌ 2SO₃; ∆H = - xKJmol-¹

Gas molecules are said to be perfectly elastic because

Which of the orbitals 4s, 4p, 4d and 4f has the lowest energy?

Elactrostatic force of attraction between sodium ion and halide ion is greatest in

Pipe-borne water is usually chlorinated in order to

Which of the following is not correct about oxidation number convention? The oxidation number of a/an

Which of the following methods is suitable for the preparation of an insoluble salt?

Consider the following equation: Ag⁺ _(aq) + CI-_(aq) → Ag⁺CI- _(s) ; ∆H = _65.7 kJmol^-1. From the equation, it can be deduced that

How many electrons are removed from Cr^2- when it is oxidized to CrO₄^2-?

In the Periodic Table, the elements that loss electrons most readily belong to

The gas evolved when dilute tetraoxosulphate (VI) acid reacts with sodium hydrogen trioxocarbonate (IV) is

30cm³ pf hydrogen at s.t.p combine with 20cm³ of oxygen to form steam according to the following equation 2H_2(g) + O_2(g) → 2H₂O_(g). Calculate the total volume of the gaseous mixture at the end of the reaction

Consider the reaction represented by the following equation: H_2(g) + 1_2(g) → 2HI_(g). The number of effective collisions of molecules of the reactants decreases as