chemistry examination for year 2023

what is chemistry

• Chemists discover naturally occurring chemicals and also make new ones never seen before

• chemistry is study of living thing

• chemistry is the study of chemical and science

• chemistry is a study of plant and anima

what is matter

• Matter deal with surface

• Matter consist two major things

• Matter is a substance made up of various types of particles that occupies physical space and has inertia

• Matter is a substance that has particles

Answer explanation

The further apart they are in the activity series, the easier it is for displacement reactions to occur. Thus, zinc easily displaces copper from copper [II] salt solution but lead which is only two elements above copper in the activity series will not displace the latter so readily.

The number of molecules of Carbon(iv)Oxide produced when 10.0g of CaCO33 is treated with 0.2dm33 of 1 Mole of HCL in the equation

CaCO33 + 2HCL ⇒  CaCl22  + H22 O + CO22  , is?

• 6.02 X 1022

• 1.00 X 1023

• 6.02 X 1023

• 6.02 X 102424

To test for chlorine ______ is used

• damp litmus paper and bromine paper

• damp litmus paper and hydrogen sulphide

• damp litmus paper and starch-iodide paper

• none of the above

The following are physical properties of chlorine except ______

• it cannot be liquefied.

• it is denser than air.

• it is sparingly soluble in water

• it is poisonous

Which of the products of these mixtures is acidic?

• HCl(g) + chloroform.

• HCl(g) + water.

• HCl(g) + Zn.

• HCl(g) + Mg.

Why is a damp blue litmus paper placed at the mouth of a jar during the preparation of hydrogen chloride?

• To determine the effect of the gas on the litmus paper

• For the litmus paper to absorb the gas.

• The litmus paper has no effect in the experiment.

• To determine when the jar is full.

DIRECTION: Choose the correct options from the lettered options.

An electrolyte conducts electricity only when ________

[i] molten.

[ii] in solution.

[iii] solid.

• [i] only.

• [ii] only.

• [i] and [ii] only.

• [i], [ii] and [iii] only.

The law that states, the mass of an element discharged during an electrolysis is directly proportional to the quantity of electricity [Q] passing through it is

• Faraday’s first law of electrolysis.

• Faraday’s second law of electrolysis.

• Faraday’s third law of electrolysis.

• Faraday’s zeroth law of electrolysis.

0.05 Faraday of electricity is passed through acidulated water using platinum electrodes. What volume of each gas is evolved?

• 0.56 dm3 of H2 and 0.28 dm3 of O2.

• 1.12 dm3 of H2 and 0.56 dm3 of O2.

• 0.224 dm3 of H2 and 0.112 dm3 of O2.

• 2.24 dm3 of H2 and 4.48 dm3 of O2.

Answer explanation

First write one of the redox equation [i.e. for hydrogen]: 2H+ + 2e- → H2; 1 mole of hydrogen will be produced by 2F of electricity? mole of hydrogen will be produced by 0.05F electricity → 0.05/2 = 0.025 moles; 1 mole of a gas gives 22.4 dm3, then 0.025 moles gives 0.025×22.4 = 0.56 dm3 of hydrogen and oxygen is half the volume of hydrogen which is 0.28 dm3