CHEMISTRY PAST QUESTIONS

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

Dehydration of ethanol produces

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

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

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

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

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

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

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

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

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

It can be concluded that gastric juice

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

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?

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

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

Petrol consists mainly of

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

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

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

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

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

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

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

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

Metals are said to be malleable because they

An exothermic reaction is one which involves

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]

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

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

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

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

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

Gas molecules are said to be perfectly elastic because

What is responsible for metallic bonding?

When alkanols react with sodium, the ga evolved is

Pipe-borne water is usually chlorinated in order to

Aluminium is extracted from

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

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

Rusting of iron is an example of

Chlorine atom forms CI by

The liquid product of the destructive distillation of coal is

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

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

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

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

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

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]

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

Chemical equilibrium is attained when

What is the shape of a molecule of CCI₄?

A radioactive solid is best stored

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

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]

The crystal layers in graphite are held together by

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

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

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

Helium is preferred to hydrogen in filling balloons because hydrogen