CHEMISTRY PAST QUESTIONS AND ANSWERS

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

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

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

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

A radioactive solid is best stored

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

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

Chemical equilibrium is attained when

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

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

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

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

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

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

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

Pipe-borne water is usually chlorinated in order to

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?

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

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

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

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

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

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

Petrol consists mainly of

What is the shape of a molecule of CCI₄?

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

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

Rusting of iron is an example of

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

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

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

Pauli Exclusion Principle is related to

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

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]

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

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

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

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

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

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

An exothermic reaction is one which involves

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

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

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)

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

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

What is responsible for metallic bonding?

Helium is preferred to hydrogen in filling balloons because hydrogen

When alkanols react with sodium, the ga evolved is

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 substances decomposes when an electric current is passed through it?

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

Gas molecules are said to be perfectly elastic because

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]

The crystal layers in graphite are held together by

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

Dehydration of ethanol produces

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

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

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