Chemistry Questions: Practice Questions and Answers

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Chemistry Practice Questions and Answers

Wooden splints F and G were placed in different zones of a Bunsen burner flame. Explain the difference between. Name the type of flame that was used in the above experiment The Diagrams below represent a list of apparatus which are commonly used in a chemistry laboratory. Give the correct order of the apparatus, using the letter only, to show the correct arrangement that can be used to prepare and investigate the nature of PH of a sample of onion solution When the air-hole is fully open, the bunsen burner produces a non-luminous flame. Explain. Draw a well labelled diagram of a non-luminous flame What is a drug? Give two drugs that are commonly abused by the youth.The diagram below shows three methods for collecting gases in the laboratory. Name the methods A and B. From the methods above, identify one that is suitable for collecting sulphur.A mixture of hexane and water was shaken and left to separate as shown in the diagram below: State the identity of; (i) P, (ii) W The diagrams below are some common laboratory apparatus. Name each apparatus and state its use.The diagram below shows some parts of a Bunsen burner. Give the functions of parts T and U.The diagram below shows the appearance of two pieces of paper placed in different parts of a non-luminous flame of a Bunsen burner and removed quickly before they caught fire. What do the experiments show about the outer region of the flame? From the above experiment, which part of the flame is better to use for heating? Give a reason.A crystal of copper (II) sulphate was placed in a beaker of water. The beaker was left standing for two days without shaking. State and explain the observations that were made.Study the information in the table below and answer questions that follow. Explain why the ionic radius of :-(a) B⁺ is greater than that of A⁺, (b) C²⁺ is smaller than that of A⁺The diagram below shows the heating curve of a pure substance. Study it and answer the questions that follow: What physical changes are taking place at points X and Z? Explain what happens to the melting point of sodium chloride added to this substance.State two differences between luminous flame and non-luminous flame. It is advisable to set a Bunsen burner to luminous flame prior to an experiment. Explain Element V has two isotopes. Two thirds of V and one third of V. What is the relative atomic mass of element V?Name the process which takes place when: Solid Carbon (Iv) Oxide (dry ice) changes directly into gas. A red litmus paper turns white when dropped into chlorine water. Propene gas molecules are converted into a giant molecule.A sample of copper turnings was found to be contaminated with copper (II) oxide. Describe how a sample of copper metal can be separated from the mixture Copper (II) oxide and charcoal are black solids. How would you distinguish between the two solids?What is chromatography? Give two applications of chromatography.The following refers to element Y. Given that isotope C contains 31 neutrons in its nucleus find the number of protons in isotope B.The table below shows the relative atomic masses and the percentage abundance of the isotopes L1 and L2 of element L. Calculate the relative atomic mass of element K.Without using any laboratory chemical, describe a simple laboratory experiment to distinguish between calcium hydrogen carbonate and sodium hydrogen carbonate An element M has two isotopes ⁶³M and ⁶⁵M . The relative atomic mass of the naturally occurring is 63.55. Calculate the percentage of each isotope.Cooking oils comprise of a mixture of compounds which have a boiling point range of 23°C to 27°C. What evidence is then to support the statement that cooking oil is a mixture? Name another experimental technique that could be used to confirm your answer in part (i) above A form 1 student carried out the separation as shown in the set-up below. Identify the method above. Give one of its disadvantages. Name a mixture which can be separated by the set-up above.What is meant by melting point and boiling point of a substance?The apparatus below were used by a student to study the effect of heat on hydrated copper II sulphate. What is the role of the ice cold water? Name liquid P. What observation is made in the boiling tube?Give reasons why a luminous flame is not used for heating purposes An oxide of element G has the formula as G₂O₃. State the valency of element G. In which group of the periodic table is element G?State the criteria for determining the purity of a substance A mixture contains ethene, Hydrogen and ammonia gases. Explain how a sample of hydrogen gas can be obtained from this mixture.The table below gives information about the ions T⁺ and Z^2-. How many protons are there in the nucleus of elements T and Z?A student left some crushed fruit mixture with water for some days. He found the mixture had fermented. He concluded that the mixture was contaminated with water and ethanol with boiling point of 100°C and 78°C respectively. The set-up of apparatus below are used to separate the mixture. Name the piece of apparatus labelled W ...The set-up below was used to separate a mixture. Name the apparatus missing in the set-up. Give one example of mixture T. What is the name of this method of separation?The diagram below shows a set-up used by a student to find out what happens when Copper (II) sulphate crystals are heated. State the observations made when the blue copper (II) sulphate crystals are heated. Identify liquid Y and write an equation for its formation...Name three frequently abused drugs. State two long term effects of drug abuse.Define Chemistry. Give three importance of studying Chemistry.The following are laboratory apparatus used in Chemistry. Name them and give their uses. Give two reasons why most laboratory apparatus are made of glass.What is a flame? The following diagrams represent the two types of flames produced by a bunsen burner. Identify the flames (a) and (b)...Sam, a form one student at Heru academy accidentally mixed sulphur and iron filings. Suggest an appropriate method of separation you would advice him to use to separate the mixture...Majaliwa, a form one student at Kanga High School wanted to separate and obtain iodine and sodium chloride (common table salt) from a mixture of the two. he set the experimental set up shown below. the mixture was heated for some time and left to cool. On cooling, shiny black crystals and white crystals were observed on the surface of the watch glass and in the beaker respectively...Define the following terms: A saturated solution and crystallization. Describe how copper (II) sulphate crystals can be obtained from copper (II) sulphate solution.What is a mixture? State two physical means of separating a mixture.The chromatography below shows the constituents of a flower extract using an organic solvent. Name a possible organic solvent you can use for this experiment. State one property that makes the red pigment to move the furthest distance from M...Study the information below and answer the questions that follow. Describe how the mixture of solid R, S, and V can be separated Given a mixture of lead (II) oxide, ammonium chloride and sodium chloride, describe how this mixture can be separated to obtain a sample of each.The setup below was used to separate two miscible liquids Q and T. (Boling points; Q =98° C, T=78°C). Identify the mistakes in the setup above.Name the process which takes place when: Solid Carbon (IV) oxide (dry ice) changes directly into gas. A red litmus paper turns white when dropped into chlorine water. Propene gas molecules are converted into a giant molecule.The following diagram shows a paper chromatogram of substances A, B, C, and D which are coloured. Indicate the solvent front on the chromatogram. Which substance is pure? Substance E is a mixture of C and D. Indicate its chromatogram in the diagram.Study the information below and answer the following questions. A mixture contains three solids A, B, and C. The solubility of these solids in different liquids is as shown below: Explain how you will obtain sample C from the mixture.State and explain the observations made when iodine crystals is heated in a boiling tube?The table below shows solutions A, B and C are tested and observations records as shown. Using the table above, name an acid. How does the pH value of 1M potassium hydroxide solution compare with that of 1M aqueous ammonia? Explain The information below gives PH values of solutions V, W, X, Y Z. Which solution is likely to be: Calcium hydroxide? Rain water? Which solution would react most vigorously with Zinc carbonate?Complete the table below to show the colour of the given indicator in acidic and basic solutions. How does the PH value of 0.1M potassium hydroxide solution compare with that of 0.1M aqueous ammonia? Explain.Use the information given below to answer the questions that follow: Which of the solutions would be used to relieve a stomach upset caused by indigestion? Which solution is likely to be: Dilute sulphuric acid? Sodium hydroxide solution?Solid copper (II) oxide is a base although it does not turn litmus paper to blue. Explain Below are the pH values of 4 types of medicine represented by letters P, Q, R and S. It is not advisable to use S when a patient has indigestion. Explain. What is the role of chemistry in drug manufacture?Explain why very little Carbon (IV) oxide gas is evolved when dilute sulphuric (VI) acid is added to lead (II) carbonate.State one commercial use of Calcium Oxide.The following data gives the pH values of some solutions. What colour change would occur in solution P on addition of two drops of phenolphthalein indicator? State the pH value of a resulting solution when equal moles of solution P and R react.In an experiment, ammonia gas was prepared by heating ammonium salt with an alkali. After drying, ammonia gas was collected at room temperature and pressure. What is meant by the term alkali? Explain using physical properties of the gas why ammonia is not collected by downward delivery.The figure below shows a paper that was placed horizontally across the middle of a non-luminous flame. Explain on the observation made.The table below shows PH values of solutions A, B, C and D. Which solution produces bubbles with zinc metal. Explain. Select any pair that would react to form a solution of PH = 7.Using dot(.) and crosses (x) to represent electrons, show bonding in the compounds formed when the following elements react (Si=14, Na=11 and C1 = 17). Sodium and chloride. Silicon and chlorine.Explain why the following substances conduct electric current: Magnesium metal, Molten magnesium chloride, and Aqueous sodium chloride.The set up below was used to collect a dry sample of a gas. Give two reasons why the set up cannot be used to collect carbon (IV) oxide.A compound of carbon, hydrogen and oxygen contains 71.12% oxygen, 2.2% hydrogen and rest carbon. If it has a relative molecular mass of 90. Determine the empirical formula of the compound C = 12, 0 = 6 H = 1. Determine the molecular formula of the compound.A mixture contains ammonium chloride, copper (ii) oxide and sodium chloride. Describe how each of the substances can be obtained from the mixture.The electronic structures for elements represented by letters A, B, C and D are: A 2.8.6; B 2.8.2; C2.8.1; D 2.8.8; Select the element which forms: A double charged cation. A soluble carbonate. Which element has the shortest atomic radius?State the Charles' law. A certain mass of a gas occupies 146dm³ at 291K and 98.31kpa. What would be its temperature if its volume is reduced to 133dm³ at 101.325kpa.Painting, oiling, galvanizing and tin plating are methods of preventing rusting. Explain the similarity of these methods in the way they prevent rusting. Explain why galvanized iron objects are better protected from rusting even when scratched.The set up below was used to prepare a gas P. Name gas P. Write the equation for the reaction that takes place in the round bottomed flask. Explain why gas P is collected over warm water.Hydrogen gas is used in the laboratory to reduce copper(II) oxide. Name any other two gases which can be used in the place of hydrogen gas.Describe how a pure sample of lead (ii) Sulphate can be prepared in the laboratory starting with lead metal.Give the systematic names of the following organic compounds.Describe a simple chemical test which can be used to distinguish the following organic compounds: C₄H₈ and C₅H₁₂ When the chlorides of Aluminium and silicon are dissolved in water, the resulting solution has a Ph of 3.0. Explain 0.84g of Aluminium reacted completely with chlorine gas. Calculate the volume of chloride gas used (molar gas volume is 24dm³, Al = 27)Graphite is one of the allotropes of carbon. Name one other element that exhibits allotropy. Explain why graphite is used as a lubricant.Study the flow diagram below and answer the questions that follow. Name the reagent used in step 1. Name the catalyst used in step II. Name X.The simplified flow chart shows some steps in the manufacture of sodium carbonate by Solvay process. Identify substance L. Name the process taking place in step II. Name one use of sodium carbonate.Under certain conditions, chlorine gas reacts with sodium hydroxide to form sodium hypochlorite. Name the conditions under which sodium hydroxide reacts with chlorine to form sodium hypochlorite. State one use of sodium hypochlorite.Write down the property of concentrated sulphuric (vi) acid which is shown by the reactions below.Write equations to show the effect of heat on each of the following: Ammonium nitrate, Lead (II) carbonate, Sodium hydrogen carbonate.The apparatus below was set up to show the catalytic oxidation of ammonia. Study the diagram and answer the questions that follow. Write an equation for the reaction that takes place in the gas jar. Why is it necessary to have a hot platinum wire in the gas jar? After sometime brown fumes are observed in the gas jar. Explain on the observation.20.0cm³ of a solution containing 4g per litre of sodium hydroxide was neutralized by 8.0cm³ of dilute sulphuric (VI) acid. Calculate the concentration of sulphuric (VI) acid in moles per litre Na=23, 0=16 H=1 s=32.Draw and name the structural formula of the compound formed when one mole of ethyne reacts with one mole of chlorine gas.The diagram below shows an incomplete set up for the laboratory preparation and collection of sulphur (IV) oxide gas. Study it and answer the questions that follow. Complete the setup to show how dry sulphur (IV) oxide gas may be collected. State the Gay Lussac's law 10cm³ of a gaseous hydrocarbon, C₂H_x required 30cm³ of oxygen for complete combustion. If steam and 20cm³ of carbon (IV) oxide were produced, what is the value of X?In an experiment a test tube full of chlorine water was inverted in chlorine water as shown in the diagram below and then the set up left in the sunlight for one day. After one day, a gas was found to have collected in the test tube. Identify the gas. What will happen to the pH of the solution in the beaker after one day? Give a reason.When a solid sample of sulphur is heated in a test tube, it changes into a liquid which flows easily; on further heating the liquid darkens and does not flow easily. Explain these observations.State and explain what would happen if a dry litmus paper was dropped in a gas jar full of chlorine.The set-up below represents apparatus that may be used to separate a mixture of two miscible liquids 'C' and 'D' whose boiling points are 80°C and 100°C respectively. Name B. What is the purpose of the thermometer? Which liquid is collected in the test tube?The table below gives some properties of gas D and E. Describe how you would obtain a sample of gas E from the mixture of gas D and E. Suggest a possible identity of gas D. Give reasons for your answer.The figure below shows a paper that was placed horizontally across the middle of a non-luminous flame. Explain on the observation made.The table below shows PH values of solutions A, B, C and D. Which solution produces bubbles with zinc metal. Explain. Select any pair that would react to form a solution of PH = 7.A concentrated Sulphuric (VI) acid has a concentration of 18.2M. Determine the volume of the concentrated acid that would be mixed with distilled water to make one litre of 2M Sulphuric (VI) acid.Two elements X and Y have their atomic number being 11 and 19 respectively. a. Show their electronic configurations. Are the elements in the same period or group, give a reason for your answer?State the type of bond in each of the following compounds: Calcium fluoride, Methane, and Ammonium ion Explain why the melting point of sodium is higher than that of potassium.State the uses of the following apparatus in chemistry: A separating funnel, A pipette, and A spatula.What is the color of phenolphthalein and methyl orange indicators in Acids and alkali?In the last stage of Solvay process a mixture of sodium hydrogen carbonate and ammonium chloride is formed. State the method used to separate the two. Write the equation showing how lime is slaked? Name any by product recycled in the Solvay process.State the Graham's Law of diffusion.Oxygen gas in the laboratory can be prepared by heating potassium nitrate. Write the equation of the reaction to show the decomposition of potassium nitrate. State One physical properties of oxygen gas. State One use of oxygen gas.An element K has relative atomic mass of 36.2. Given that the element has two isotopes, A of atomic mass 35.0 and B of atomic mass 38.0. Calculate the relative percentage abundances of each of the isotopes.Name any two non-crystalline allotropes of sulphur.Chlorine gas was bubbled through water for some time. The yellow solution formed was poured into a long glass tube and placed in the sun as shown in the diagram below. What compounds are in the yellow solution? Write an ionic equation between chlorine and aqueous iron ii chloride solution.12.0 cm³ of 0.05 M hydrochloric acid reacted with calcium hydrogen carbonate to form calcium chloride, water and carbon IV oxide. Write the chemical equation for the reaction. Calculate the number of moles of hydrochloric acid used. Determine the mass of calcium hydrogen carbonate used. (Ca = 40, C =12, H = 1,O=16).Explain each of the following observations: Soft drinks fizz when the cap is removed, Diamond does not conduct electricity while graphite does, and Pure nitric acid is colorless but during its laboratory preparation it appears yellow.Why is aqueous ammonia warmed gently? What is the color of the flame? The setup in the diagram below was used to study the reaction between magnesium ribbon and steam. Study it and answer the question that follows. Identify gas P. Write the chemical equation for the reaction that took place in the combustion tube.The following data gives the PH values of solutions P, Q and R. Which solution will produce carbon IV oxide when reacted with marble chips? Which solution would be a suitable anti-acid?The diagram below show a burning jiko in a room which has sufficient supply of oxygen. Using chemical equation, explain what happens at A and B. State the main danger of emitting excess carbon iv oxide into the atmosphere.Complete the table below filling in the Neutrons, Protons and Electrons in Ions.State Charles law The volume of a sample of nitrogen gas at temperature of 298 K and 600mmHg pressure was 4.8x10^-2M³. Calculate the temperature at which the volume of the gas would be 3.2x10^-2M³ if the pressure is constant.Use the information in the table below and answer the question that follows. xplain why both sodium and magnesium conduct electricity while phosphorus and chlorine do not. Suggest a reason why phosphorus has been assigned two melting points values.Explain why atomic radii of element in any period decreases gradually from left to right in the periodic table.When a mixture of iron filings and sulphur was heated, red glow spreads through the mixture and a dark grey solid was formed. Identify the dark grey solid formed. What observation can be made when the dark grey solid react with dilute hydrochloric acid? Write a chemical equation in which the dark grey solid is formed during heating.Below is a set up of apparatus used to react ammonia gas with iron II chloride. State the observation made in the beaker. Give a reason for using a funnel to deliver the ammonia to the beaker.The fractional distillation of liquid air usually produces nitrogen and oxygen as the major products. Describe how nitrogen gas is obtained from air (N₂= -196°C, O₂=-183°C).Give the reagents and the conditions used to prepare: Ethane gas, Ethene gas, and Ethyne.Iron is a metal and sulphur is a non-metal. Explain why it is easier to separate Iron from a mixture of iron and sulphur than from a compound of iron and sulphur.Diamond and graphite are allotropes of carbon. In terms of structure and bonding. Explain the following. Diamond is used in drilling through hard rocks. Graphite is used as a lubricant.Identify apparatus X,Y and Z. What are the uses of apparatus X and Z?Define the term hydrocarbon.Describe a chemical test to distinguish between hydrocarbons with the following molecular formula C₄H₁₀ and C₄H₈ respectively.A compound has an empirical formula C₃H₆O and a relative formula mass of 116.a. Determine its molecular formula (H = 1.0, C = 12.0, O = 16.0). b. Calculate the percentage composition of carbon by mass in the compound.Some black ink was subjected chromatographic analysis to determine its content. It was analysed alongside brown ink, red, green, yellow and blue. Name the impure the ink. Identify the ink that is not a compound to black ink.A plastic bag containing potato chips is filled with 100cm³ of air at 20°c. If it is kept in the sun, the temperature rises to 30°c. What is the final volume after warming?The apparatus shown below was set to prepare and collect hydrogen sulphide gas. Name solid C. Give a reason why warm water is used. What observation would be made if hydrogen sulphate gas was bubbled into a solution of lead (II) nitrate?The flow chart below shows the preparation of carbon (II) oxide and its reaction. Name the type of reaction that takes place between H₂C₂O₂ and conc. H₂SO₄. Write an equation for the production of B and C. State two uses of carbon (II) oxide.Element V exist as two isotopes. The relative atomic mass of a normal sample of V is 74.1. Deduce the relative percentage abundance of each Isotope.1.512g of metal carbonate XCO₃ react with 20 cm³ of 1.8M hydrochloric acid completely. calculate the relative atomic mass of element X (C = 12, O = 16).Describe the process by which nitrogen is obtained from air on a large scale.

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