Physical constants in physics

09/26/2021 0

List of constants to be used Acceleration due to gravity, g                                     9.81ms-2 Electron charge, e                                                            1.6 x10-19C Electron mass                                                                    9.11 x 10-31kg Mass of the ... Read More

A-level mechanics revision questions fully answered

09/24/2021 0

List of physical constants to be used Acceleration due to gravity, g                                     9.81ms-2 Electron charge, e                                                            1.6 x10-19C Electron mass                                                                    9.11 x 10-31kg Mass of ... Read More

Aldol condensations of carbonyl compounds

09/19/2021 0

Aldol condensations of carbonyl compounds Carbonyl compounds which contain at least one alpha hydrogen, react in presence of alkali to form hydroxyl carbonyl compounds called ... Read More

Cannizzaro reaction of aldehydes

09/19/2021 0

Cannizzaro reaction of aldehydes This is a reaction between sodium hydroxide solution and aldehydes with no α-hydrogen It’s  a self-oxidation – reduction reaction Examples Please ... Read More

Distinguishing between aldehydes and ketone

09/19/2021 0

Reagent Observation Aldehydes Ketones Fehling’s solution Brown ppt No observable change Tollen’s reagent or ammoniacal silver nitrate   Black ppt or silver mirror   No ... Read More

Reaction methyl ketone with iodine

09/19/2021 0

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Reaction of benzene with chlorine in the presence of u.v-light

09/19/2021 0

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Reaction of benzene with alkenes

09/19/2021 0

Reaction of benzene with alkenes In the presence of a mineral acid benzene react with alkenes to form alkylbenzene. Please Subscribe to promote this website. ... Read More

Reaction of benzene with alkanoylhalides

09/19/2021 0

The reaction requires an electron carrier and produces ketones Example Please Subscribe to promote this website. Subscription is free Share with a friend Your comment ... Read More

Reaction of benzene with alkyl halides like chloromethane

09/19/2021 0

  This is a reaction of benzene with an alkyl halide to give an alkyl benzene. The reaction is catalysed by electron carriers such as ... Read More

Reaction of benzene with halogens, chlorine, bromine, iodine

09/19/2021 0

Reaction of benzene with halogens This requires the use of electron carriers (AlCl3, FCl3) as catalysts. The electron carrier is usually a halide of iron ... Read More

Sulphonation of benzene or reaction of benzene with sulphuric acid

09/19/2021 0

Sulphonation of benzene is the introduction of the sulphonic group (-SO3H) on to the benzene ring. It’s done by heating benzene with concentrated suphuric acid. A ... Read More

Nitration of benzene or reaction of benzene with nitric acid

09/19/2021 0

Nitration of benzene This is the introduction of the nitro group on the benzene ring using a hot mixture of concentrated sulphuric acid and concentrated ... Read More

Preparation of phenol form cumene or 2-phenylpropane

09/19/2021 0

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Distinguishing between primary, secondary and tertiary amines

09/19/2021 0

Distinguishing between primary, secondary and tertiary amines Reagent: nitrous acid (NaNO2, HCl (0-50C)) Observation (i) Primary amine: effervescence Equation RNH2 + NaNO2 + 2HCl     ... Read More

Explain why phenylamine is a weaker base than ammonia and ammonia is a weaker base than dimethylamine

09/19/2021 0

Solution Trimethylamine is a stronger base than ammonia because the methyl groups donate electrons to the nitrogen atom. This increases the density of alone pair ... Read More

Basic trendsof amines

09/19/2021 0

Bacisity of amines   Like ammonia, amines dissolve in water to form alkaline solution. RNH2  + H2O ↔ RN+H3 + OH-(aq)   The strength of ... Read More

Variation of boiling and melting points of amines

09/19/2021 0

Variation of boiling and melting points of amines Amines are polar compounds and therefore have higher melting and boiling points than non-polar compounds of similar ... Read More

Reaction of terminal alkyne with ammoniacal silver nitrate or copper 1 nitrate

09/19/2021 0

Alkynes with a triple bond at the end of the chain react with ammoniacal silver nitrate or ammoniacal copper I chloride to form white precipitate ... Read More

Reaction of ethyne with water

09/19/2021 0

The reaction ethyne with water is catalysed by mercury (II) sulphate and dilute sulphuric acid. Carbonyl compounds are formed. Example Mechanism Please Subscribe to promote ... Read More

Reduction of alkynes

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Preparation of ethyne from ethanol

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Preparation of ethyne from 1, 2-dibromoethane

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Preparation of ethyne from carbon

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Describe Searle’s method of determining the thermal conductivity of a good conductor of heat.

09/18/2021 0

Specimen bar AB of mean diameter, d, is heated by steam at end A and cooled by water at end B as shown above The ... Read More

Explain how cooking at a pressure of 76cm of mercury and temperature of 1000C may be achieved on top of high mountains. 

09/18/2021 0

Cooking pans are fitted with lids that possess safety valves that open when the pressure exceeds 76cmmmHg. During cooking the vapour pressure inside the cooking ... Read More

Describe an experiment to show that a liquid boils only when its saturated vapor pressure is equal to external pressure (05marks)

09/18/2021 0

Experiment to show that a liquid boils off when its saturated vapour pressure equals the external pressure Air is trapped in the closed limb of ... Read More

Using kinetic theory, explain boiling of a liquid 

09/18/2021 0

Using kinetic theory, explain boiling of a liquid Molecules of a liquid through moving randomly have attractive forces between them. When a liquid is heated, ... Read More

Explain the significance of latent heat in regulation of body temperature (03marks)

09/18/2021 0

Explain the significance of latent heat in regulation of body temperature (03marks) On a hot day, the body sweats. Evaporation occurs at the surface of ... Read More

State the laws of black body radiation (02marks)

09/18/2021 0

State the laws of black body radiation (02marks) The wavelength λm at which maximum energy is radiated for temperature, T ia such that λmT = ... Read More

Explain in terms of specific heat capacity why water is used in a car radiator other than any other liquid. (02mark)

09/18/2021 0

Explain in terms of specific heat capacity why water is used in a car radiator other than any other liquid. (02mark) Water has very high ... Read More

With the aid of a labelled diagram, describe how the room temperature can be measured using uncalibrated resistance thermometer. (06marks)

09/18/2021 0

With the aid of a labelled diagram, describe how the room temperature can be measured using uncalibrated resistance thermometer. (06marks) Place the resistance thermometer in ... Read More

State Prevost’s theory of heat exchange. (01mark)

09/18/2021 0

State Prevost’s theory of heat exchange. (01mark) A body at constant temperature is in of dynamic equilibrium with its surroundings. The rate of radiation being ... Read More

Explain why the specific latent heat of fusion and specific latent heat of vaporization of a substance at the same pressure are different. (04marks)

09/18/2021 0

Explain why the specific latent heat of fusion and specific latent heat of vaporization of a substance at the same pressure are different. (04marks) Change ... Read More

Explain why the temperature of a liquid does not change when the liquid is boiling? (02marks)

09/18/2021 0

Explain why the temperature of a liquid does not change when the liquid is boiling? (02marks) When the liquid boils, there is change in a ... Read More

Why is the distinction between specific heat capacity at constant pressure and that at constant volume important for gases, but less important for solids and liquids? (04marks)

09/18/2021 0

Why is the distinction between specific heat capacity at constant pressure and that at constant volume important for gases, but less important for solids and ... Read More

Define the term specific heat capacity and internal energy and state their units.

09/18/2021 0

Define the term specific heat capacity and internal energy and state their units. (03marks)   Specific heat capacity is the amount of heat required to ... Read More

Explain the greenhouse effect and how it is related to global warming. (04marks)

09/18/2021 0

Explain the greenhouse effect and how it is related to global warming. (04marks) Short wavelength radiation from the sun passes through glass of green house. ... Read More

State one advantage and one disadvantage of the resistance thermometer

09/18/2021 0

State one advantage and one disadvantage of the resistance thermometer. (01mark) Advantage - measures a wide range of temperatures - very accurate   Disadvantages unsuitable ... Read More

Describe an experiment to verify Boyles’ law

09/18/2021 0

Describe an experiment to verify Boyles’ law   air in the closed limb of a U-tube barometer as shown above mercury is poured to a ... Read More

Heat Physic (A-level)

09/17/2021 0

Heat This is a form of energy which that rises the temperature of substances. Means of heat transfer Conduction Conduction is the process of heat ... Read More

Outline the experimental evidences for the quantum theory of matter.

09/05/2021 2

Outline the experimental evidences for the quantum theory of matter. The quantum theory of matter states that energy of a radiation exists in discrete packets ... Read More

What is  Nuclear fusion?

09/05/2021 0

What is  Nuclear fusion? Nuclear fusion is the combination of light nuclei to form a heavier nucleus accompanied by release of energy. Please Subscribe to ... Read More

What is nuclear fission?

09/05/2021 0

What is nuclear fission? Nuclear fission is the splitting of heavy unstable nucleus into two nuclei accompanied by release of energy. Please Subscribe to promote ... Read More

Describe an experiment to verify Einstein’s equation for the photoelectric effect and explain how Plank’s constant may be obtained from the experiment.

09/05/2021 0

Describe an experiment to verify Einstein’s equation for the photoelectric effect and explain how Plank’s constant may be obtained from the experiment. A radiation of ... Read More

Explain how intensity and penetrating power of X-rays from X-ray tube would be affected by increasing the high tension potential difference across the tube 

09/05/2021 0

Explain how intensity and penetrating power of X-rays from X-ray tube would be affected by increasing the high tension potential difference across the tube  Penetrating ... Read More

Explain how intensity and penetrating power of X-rays from X-ray tube would be affected by changing the filament current 

09/05/2021 0

Explain how intensity and penetrating power of X-rays from X-ray tube would be affected by changing the filament current  When the filament current is increased, ... Read More

Explain the term stopping potential as applied to photo electric effect. 

09/05/2021 0

Explain the term stopping potential as applied to photo electric effect.  It is the minimum potential difference between the anode and the cathode that reduces ... Read More

Sketch the current –voltage characteristic of the Geiger- Muller tube and explain its main features.

09/05/2021 0

Sketch the current –voltage characteristic of the Geiger- Muller tube and explain its main features.  OA – the operating voltage is not enough to attract ... Read More

What are radioisotopes? 

09/05/2021 0

What are radioisotopes?  Radioisotope are radioactive atoms of the same element having the same atomic number but different atomic mass Please Subscribe to promote this ... Read More

State two disadvantages of discharge tubes when used to study cathode rays. 

09/05/2021 0

State two disadvantages of discharge tubes when used to study cathode rays.  A gas is needed at very low pressure which may not be easy ... Read More

Describe an experiment to measure the ratio of the charge to mass of an electron

09/05/2021 0

Describe an experiment to measure the ratio of the charge to mass of an electron The electrons are produced thermionically by a hot filament cathode ... Read More

Explain, using suitable sketch graph, how X-ray spectrum in an X-ray tube are formed. 

09/05/2021 0

Explain, using suitable sketch graph, how X-ray spectrum in an X-ray tube are formed.  The spectrum consists of two major components, i.e. the continuous (background) ... Read More

Explain the purpose of Argon gas at low pressure of the following in a Geiger-Muller tube

09/05/2021 0

Explain the purpose of Argon gas at low pressure of the following in a Geiger-Muller tube  Argon form ions when it is struck by ionizing ... Read More

 Explain the purpose of a thin mica window of the following in a Geiger-Muller tube

09/05/2021 0

 Explain the purpose of a thin mica window of the following in a Geiger-Muller tube    To allow easy entry of ionizing particles in the ... Read More

With the aid of an equivalent circuit of a triode as an amplifier, obtain an expression for voltage gain

09/05/2021 0

With the aid of an equivalent circuit of a triode as an amplifier, obtain an expression for voltage gain Please Subscribe to promote this website. ... Read More

Draw a labelled circuit to show a triode being used as a single-stage voltage amplifier.

09/05/2021 0

Draw a labelled circuit to show a triode being used  as a single-stage voltage amplifier. Please Subscribe to promote this website. Subscription is free Share ... Read More

Sketch and describe the collector-current against collector-emitter voltage characteristic of a junction transistor.

09/05/2021 0

Sketch and describe the collector-current against collector-emitter voltage characteristic of a junction transistor. For small values of V, Ic increases linearly with V but strongly ... Read More

Describe the structure of a junction transistor.

09/05/2021 0

Describe the structure of a junction transistor. A transistor consist of 3 layers of P- and n- semiconductors called respectively emitter, base and collector. The ... Read More

Describe briefly the mechanism of thermionic emission.

09/05/2021 0

Describe briefly the mechanism of thermionic emission. High temperature raises the kinetic energy of free electrons in metallic lattice and make them to escape from ... Read More