1. Why should a magnesium ribbon be cleaned before burning in air ? 2. Write the balanced equation for the following chemical reactions. (i) Hydrogen + Chlorine → Hydrogen chloride (ii) Barium chloride + Aluminium sulphate → Barium sulphate + Aluminium chloride (iii) Sodium + Water → Sodium hydroxide + Hydrogen 3. Write a balanced chemical equation with state symbols for the following reactions : (i) Solutions of barium chloride and sodium sulphate in water react to give insoluble barium sulphate and the solution of sodium chloride. (ii) Sodium hydroxide solution (in water) reacts with hydrochloric acid solution (in water) to produce sodium chloride solution and water. 4. A solution of a substance ‘X’ is used for white washing. (i) Name the substance ‘X’ and write its formula. (ii) Write the reaction of the substance ‘X’ named in (i) above with water. 5. Why is the amount of gas collected in one of the test tubes in text book Activity 1.7 (i.e., electrolysis of water) double of the amount collected in the other? Name this gas. 6. Why does the colour of copper sulphate solution change when an iron nail is dipped in it ? OR An iron nail is dipped in the solution of copper sulphate for about 30 minutes. State the change in colour observed. Give reason for the change. 7. Give an example of a double displacement reaction other than the one given in Activity 1.10 . 8. Identify the substances that are oxidised and the substances which are reduced in the following reactions. (i) 4Na(s) + O2(g) → 2Na2O(s) (ii) CuO (s) + H2(g) → Cu (s) + H2O(l) 9. Which of the statements about the reaction below are incorrect ? 2 PbO(s) + C(s) → 2Pb (s) + CO2(g) (a) Lead is getting reduced. (b) Carbon dioxide is getting oxidised. (c) Carbon is getting oxidised. (d) Lead oxide is getting reduced. (i) (a) and (b) (ii) (a) and (c) (iii) (a), (b) and (c) (iv) All 10. Question 2 Fe2O3 + 2Al → Al2O3 + 2Fe The above reaction is an example of a (a) combination reaction (b) double displacement reaction (c) decomposition reaction (d) displacement reaction 11. What happens when dilute hydrochloric acid is added to iron filings ? Tick the correct answer : (a) Hydrogen gas and iron chloride are produced. (b) Chlorine gas and iron hydroxide are produced. (c) No reaction takes place. (d) Iron salt and water are produced 12. What is a balanced chemical equation ? Why should chemical equations be balanced ? 13. Translate the following statements into chemical equations and then balance them. (a) Hydrogen gas combines with nitrogen to form ammonia. (b) Hydrogen sulphide gas burns in air to give water and sulphur dioxide. (c) Barium chloride reacts with aluminium sulphate to give aluminium chloride and a precipitate of barium sulphate. (d) Potassium metal reacts with water to give potassium hydroxide and hydrogen gas. 14. Balance the following chemical equations : (a) HNO3 + Ca (OH)2 → Ca (NO3)2 + H2O (b) NaOH + H2SO4 → Na2SO4 + H2O (c) NaCl + AgNO3 → AgCl + NaNO3 (d) BaCl2 + H2SO4 → BaSO4 + HCl 15. Write the balanced chemical equations for the following reactions : (a) Calcium hydroxide + Carbon dioxide → Calcium carbonate + Water (b) Zinc + Silver nitrate → Zinc nitrate + Silver (c) Aluminium + Copper chloride → Aluminium chloride + Copper (d) Barium chloride + Potassium sulphate → Barium sulphate + Potassium chloride 16. Write the balanced chemical equation for the following and identify the type of reaction in each case : (a) Potassium bromide (aq) + Barium iodide (aq) → Potassium iodide (aq) + Barium (b) Zinc carbonate(s) → Zinc oxide (s) + Carbon dioxide (g) bromide(s) (c) Hydrogen (g) + Chloride (g) → Hydrogen chloride (g) (d) Magnesium (s) + Hydrochloric acid (aq) → Magnesium chloride (aq) + Hydrogen (g) 17. What does one mean by exothermic and endothermic reactions ? Give examples. 18. Why is respiration considered an exothermic reaction ? Explain. 19. Why are decomposition reactions called the opposite of combination reactions? Write equations for these reactions. 20. Write one equation each for the decomposition reactions where energy is supplied in the form of heat, light or electricity. OR Decomposition reactions require energy either in the form of heat or light or electricity for breaking down the reactants. Write one equation each for decomposition reactions where energy is supplied in the form of heat, light and electricity. 21. What is the difference between displacement and double displacement reactions? Write equations for these reactions. 22. In the refining of silver, the recovery of silver from silver nitrate solution involved displacement by copper metal. Write down the reaction involved. 23. What do you mean by a precipitation reaction ? Explain by giving examples. 24. Explain the following in terms of gain or loss of oxygen with two examples each: (a) Oxidation and (b) Reduction. 25. A shiny brown coloured element ‘X’ on heating in air becomes black in colour. Name the element ‘X’ and the black coloured compound formed. 26. Why do we apply paint on iron articles ? 27. Oil and fat containing food items are flushed with nitrogen. Why ? 28. Explain the following terms with one example each (a) Corrosion, (b) Rancidity
Extra Questions
1. How does the food become rancid?
2. What is a balanced chemical equation?
3. Name two salts that are used in black and white photography.
4. Which chemical process is used for obtaining a metal from its oxide?
5. When carbon dioxide is passed through lime water, it turns milky, why?
6. Identify the most reactive and least reactive metal: Al, K, Ca, Au.
7. Why is it necessary to balance a chemical equation?
8. During electrolysis of water, the gas collected in one test tube is double than the other, why?
9. Represent decomposition of ferrous sulphate with the help of balanced chemical equation.
10. A teacher took a few crystals of sugar in a dry test tube and heated the test tube over a flame. The colour of sugar turned black. Explain why?
11. ame two metals which do not get corroded.
12. Why is a magnesium ribbon cleaned before burning?
13. The gases hydrogen and chlorine do not react with each other even if kept together for a long time. However, in the presence of sunlight, they readily combine. What actually happens?
14. What happens chemically when quick lime is added to water?
15. Write chemical equations for the reactions taking place when:
(i) Iron reacts with steam
(ii) Magnesium reacts with dilute HCl
(iii) Copper is heated in air
Multiple Choice Questions
Which of the following are exothermic processes?
(i) Reaction of water with quick lime
(ii) Dilution of an acid
(iii) Evaporation of water
(iv) Sublimation of camphor (crystals)
(a) (i) and (ii)
(b) (ii) and (iii)
(c) (i) and (iv)
(d) (iii) and (iv)
A teacher gave two test tubes to the students, one containing water and the other containing sodium hydroxide. She asked them to identify the test tube containing sodium hydroxide solution. Which one of the following can be used for the identification?
(a) Blue litmus
(b) Red litmus
(c) Sodium carbonate solution
(d) Dilute hydrochloric acid
Which of the following is not physical change?
(a) Boiling of water to give water vapour
(b) Melting of ice to give water
(c) Dissolution of salt in water
(d) Combustion of Liquefied Petroleum Gas (LPG)
Which of the following is true for an unbalanced chemical equation?
(a) Number of atoms is equal on both sides of the equation
(b) Number of atoms is less on the left side of the equation
(c) Number of atoms is more on the right side of the equation
(d) Both (b) and (c).
Which of the following is Not True with respect to the neutralisation reaction?
(a) Salt is formed.
(b) Reaction occurs between an acid and a base.
(c) Reactive element displaces less reactive element.
(d) Reactants are in gaseous state.
Combustion reactions are always
(a) Exothermic
(b) Endothermic
(c) Sometimes exothermic
(d) Both (a) and (b)
Barium chloride on reacting with ammonium sulphate forms barium sulphate and ammonium chloride. Which of the following correctly represents the type of the reaction involved?
(i) Displacement reaction
(ii) Precipitation reaction
(iii) Combination reaction
(iv) Double displacement reaction
(a) (i) only
(b) (ii) only
(c) (iv) only
(d) (ii) and (iv)
Which one of the following processes involve chemical reactions?
(a) Storing of oxygen gas under pressure in a gas cylinder
(b) Liquefaction of air
(c) Keeping petrol in a China dish in the open
(d) Heating copper wire in presence of air at high temperature
In the double displacement reaction between aqueous potassium iodide and aqueous lead nitrate, a yellow precipitate of lead iodide is formed. While performing the activity if lead nitrate is not available, which of the following can be used in place of lead nitrate?
(a) Lead sulphate (insoluble)
(b) Lead acetate
(c) Ammonium nitrate
(d) Potassium sulphate
In which of the following chemical equations, the abbreviations represent the correct states of the reactants and products involved at reaction temperature?
(a) 2H2(l) + O2(l) → 2H2O(g)
(b) 2H2(g) + O2(l) → 2H2O(l)
(c) 2H2(g) + O2(g) → 2H2O(l)
(d) 2H2(g) + O2(g) → 2H2O(g)
NCERT Questions
1. You have been provided with three test tubes. One of them contains distilled water and the other two contain an acidic solution and a basic solution, respectively. If you are given only red litmus paper, how will you identify the contents of each test tube ?
2. Why should curd and sour substances not be kept in brass and copper vessels ?
3. Which gas is usually liberated when an acid reacts with a metal ?
Illustrate with an example. How will you test for the presence of this gas?
4. Metal compound A reacts with dilute hydrochloric acid to produce effervescence. The gas evolved extinguishes a burning candle. Write a balanced chemical equation for the reaction if one of the compounds formed is calcium chloride.
5. Why do HCl, HNO3, etc show acidic characters in aqueous solutions while solutions of compounds like alcohol and glucose do not show acidic character ?
6. Why does an aqueous solution of an acid conduct electricity ?
7. Why does dry HCl gas not change the colour of the dry litmus paper ?
8. While diluting an acid, why is it recommended that the acid should be added to water and not water to the acid ?
9. How is the concentration of hydronium ions (H3O+) affected when a solution of an acid is diluted ?
10. How is the concentration of hydroxide ions (OH−) affected when excess base is dissolved in a solution of sodium hydroxide ?
11. You have two solutions A and B. The pH of solution A is 6 and pH of solution B is 8. Which solution has more hydrogen ion concentration? Which of this is acidic and which one is basic ?
12. What effect does the concentration of H+ (aq) ions have on the nature of the solution ?
13. Do basic solutions also have H+ (aq) ions ? If yes, then why are these basic ?
14. Under what soil condition do you think a farmer would treat the soil of his fields with quick lime (calcium oxide) or slaked lime (calcium hydroxide) or chalk (calcium carbonate) ?
15. What is the common name of the compound CaOCl2 ?
16. Name the substance which on treatment with chlorine yields bleaching powder.
17. Name the sodium compound which is used for softening hard water.
18. What will happen if a solution of sodium hydrogen carbonate is heated. Give the equation of the reaction involved ?
19. Write an equation to show the reaction between plaster of Paris and water.
20. A solution turns red litmus blue, its pH is likely to be
(a) 1
(b) 4
(c) 5
(d) 10
21. A solution reacts with crushed-egg shells to give a gas that turns lime water milky. The solution contains
(a) NaCl
(b) HCl
(c) LiCl
(d) KCl
22. 10 mL of a solution of NaOH is found to be completely neutralised by 8 mL of a given solution of HC1. If we take 20 mL of the same solution of NaOH, the amount of HCl solution (the same solution as before) required to neutralise it will be
(a) 4 mL
(b) 8 mL
(c) 12 mL
(d) 16 mL
23. Which one of the following types of medicines is used for treating indigestion?
(a) Antibiotic
(b) Analgesic
(c) Antacid
(d) Antiseptic
24. Write word equations and then balanced equations for the reaction taking place when
(a) dilute sulphuric acid reacts with zinc granules
(b) dilute hydrochloric acid reacts with magnesium ribbon
(c) dilute sulphuric acid reacts with aluminium powder
(d) dilute hydrochloric acid reacts with iron filing
25. Compounds such as alcohol and glucose also contain hydrogen but are not categorised as acids. Describe an activity to prove it.
26. Why does distilled water not conduct electricity, whereas rainwater does ?
27. Why do acids not show acidic behaviour in the absence of water ?
28. Five solutions A, B, C, D and E when tested with universal indicator showed pH as 4, 1, 11, 7 and 9 respectively. Which solution is
(a) Neutral
(b) Strongly alkaline
(c) Strongly acidic
(d) Weakly acidic
(e) Weakly alkaline
Arrange the pH in increasing order of hydrogen ion concentration.
29. Equal lengths of magnesium ribbons are taken in test tubes A and B. Hydrochloric acid (HCl) is added to test tube A, while acetic acid (CH3COOH) is added to test tube B. In which test tube will the fizzing occur more vigorously and why ?
30. fresh milk has a pH of 6. How do you think the pH will change as it turns into curd ? Explain your answer.
31. A milkman adds a very small amount of baking soda to fresh milk.
(a) Why does he shift the pH of the fresh milk from 6 to slightly alkaline ?
(b) Why does this milk take a long time to set as curd ?
32. Plaster of Paris should be stored in a moisture proof container. Explain why?
33. What is a neutralisation reaction ? Give two examples.
34. Give two important uses of washing soda and baking soda.
Extra Questions
1. Define alkali.
2. How does acid rain harm aquatic life ?
3. How is bleachin powder produced ?
4. Why does solution of an acid in water conduct electricity ?
5. What are products of reaction of acid with a base ?
6. Name the acids present in olive oil, vinegar.
7. What do you mean by water of crystallisation. How many water molecules of water are present in gypsum ?
8. Name any two natural materials that can be used to prepare indicator.
9. Write two uses of each:
I. Washing soda
II. Plaster of paris
10. Why sodium hydrogencarbonate is used in making bread or cake ?
Multiple Choice Questions
1. Stearicacid is present in
a. Urine
b. Apple
c. Fats
d. Curd
2. Vitamin 'C' is one form of
a. Formic acid
b. Ascorbic acid
c. Tartaric acid
d. Oxalic acid
3. Generally the nature of a non-metal oxide is
a. Acidic
b. Basic
c. Neutral
d. Amphoteric
4. What is the range of pH in human body?
a. 5 - 6
b. 7 - 8.2
c. 6 - 7
d. 7 - 7.8
5. Antacid tablets usually contain
a. Mg(OH)2
b. NaOH
c. CaCO3
d. Ca(OH)2
6. Salt of strong acid and strong base will have pH equal to
a. 7
b. 5
c. 11
d. 14
7. A solution conducts electricity, it may contain
a. Glucose
b. Alcohol
c. Urea
d. Hydrochloric acid
8. Washing soda is an example of
a. Acidic salt
b. Basic salt
c. Neutral salt
d. Mixed salt
9. Which of these is a weak base?
a. NaOH
b. KOH
c. NH4OH
d. LiOH
10. Which one is not an acid-base indicator?
a. Litmus
b. Methyl orange
c. Hydrochloric acid
d. Phenolphthalein
NCERT Questions
1. Give an example of a metal which :
(i) is a liquid at room temperature.
(ii) can be easily cut with a knife.
(iii) is the best conductor of heat.
(iv) is a poor conductor of heat
2. Explain the meanings of malleable and ductile.
3. Why is sodium kept immersed in kerosene oil ?
4. Write equations for the reactions of
(i) iron with steam.
(ii) calcium and potassium with water.
5. Samples of four metals A, B, C and D were taken and added to the following solution one by one.
The results obtained have been tabulated as follows :
Metal Iron (II) sulphate Copper (II) sulphate Zinc sulphate Silver nitrate
A No reaction Displacement
B Displacement No reaction
C No reaction No reaction No reaction Displacement
D No reaction No reaction No reaction No reaction
Use the Table above to answer the following questions about metals A, B, C and D.
(i) Which is the most reactive metal ?
(ii) What would you observe if B is added to a solution of copper (II) sulphate?
(iii) Arrange the metals A, B, C and D in the order of decreasing reactivity.
6. Which gas is produced when dilute hydrochloric acid is added to a reactive metal ? Write the chemical reaction when iron reacts with dilute H2SO4.
7. What would you observe when zinc is added to a solution of iron (II) sulphate ? Write the chemical reaction that takes place.
8. (i) Write the electron dot structures for sodium, oxygen and magnesium.
(ii) Show the formation of Na2O and MgO by the transfer of electrons.
(iii) What are ions present in these compounds?
9. Why do ionic compounds have high melting points ?
(iii) What are ions present in these compounds?
10. Define the following terms : (i) Mineral, (ii) Ore and (iii) Gangue
11. Name two metals which are found in nature in the free state.
13. What chemical process is used for obtaining a metal from its oxide.
14. Metallic oxides of zinc, magnesium and copper were heated with the following metals :
Metal Zinc Magnesium Copper
1. Zinc oxide
2. Magnesium oxide
3. Copper oxide
15. In which cases will you find displacement reactions taking place ?
16. Which metals do not corrode easily ?
17. What are alloys ?
18. Which of the following pairs will give displacement reactions ?
(a) NaCl solution and copper metal.
(b) MgCl2 solution and aluminium metal.
(c) FeSO4 solution and silver metal.
(d) AgNO3 solution and copper metal.
19. Which of the following methods is suitable for preventing an iron frying pan from rusting ?
(a) Applying grease
(b) Applying paint.
(c) Applying a coating of zinc
(d) All the above.
20. An element reacts with oxygen to give a compound with a high melting point. This compound is also soluble in water. The element is likely to be
(a) calcium
(b) carbon
(c) silicon
(d) iron
21. Food cans are coated with tin and not with zinc because
(a) zinc is costlier than tin
(b) zinc has a higher melting point than tin
(c) zinc is less reactive than tin
(d) zinc is more reactive than tin
22. You are given a hammer, a battery, a bulb, wires and a switch.
(a) How could you use them to distinguish between samples of metals and non-metals?
(b) Assess the usefulness of these tests in distinguishing between metals and non-metals.
23. What are amphoteric oxides ? Give two examples of amphoteric oxides ?
OR
Write chemical equations that show aluminium oxide reacts with acid as well as base.
24. Name two metals which will displace hydrogen from dilute acids and two metals which will not.
25. In the electrolytic refining of a metal M, what would you take as the anode, the cathode and the electrolyte ?
26. Pratyush took sulphur powder on a spatula and heated it. He collected the gas evolved by inverting a test tube over it, as shown in the figure.
(a) What will be the action of gas on
(i) dry litmus paper ?
(ii) moist litmus paper ?
(b) Write a balanced chemical equation for the reaction taking place.
27. State two ways to prevent the rusting of iron.
28. What type of oxides are formed when non-metals combine with oxygen ?
29. Give reasons :
(a) Platinum, gold and silver are used to make jewellery.
(b) Sodium, potassium and lithium are stored under oil.
(c) Aluminium is a highly reactive metal, yet it is used to make utensils for cooking.
(d) Carbonate and sulphide ores are usually converted into oxides during the process of extraction.
30. You must have seen tarnished copper vessels being cleaned with lemon or tamarind juice. Explain why these sour substances are effective in cleaning the vessels.
31. Differentiate between metal and non-metal on the basis of their chemical properties.
32.A man went door-to door posing as a goldsmith. He promised to bring back the glitter of old and dull gold ornaments. An unsuspecting lady gave a set of gold bangles to him which he dipped in a particular solution. The bangles sparkled like new but their weight was reduced drastically. The lady was upset but after a futile argument the man beat a hasty repeat. Can you play the detective to find out the nature of the solution he has used?
33. Give reasons why copper is used to make hot water tanks and not steel (an alloy of iron).
34. What are amphoteric oxides? Give two examples of amphoteric oxides.
35. Name two metals, which will displace hydrogen from dilute acids, and two metals which will not.
36. In the electrolytic refining of a metal M, what would you take as the anode, the cathode and the electrolyte?
37. State two ways to prevent the rusting of iron.
38. What types of oxides are formed when non-metals combine with oxygen?
39. Give reason
i. Metals replace hydrogen from dilute acids, where as non-metals do not.
ii. Carbonate and sulphide ores are usually converted into oxides during the process of extraction.
40. Differentiate between metals and non-metals on the basis of their chemical properties.
41. Explain why the surface of some metals acquires a dull appearance when exposed to air for a long time.
42. State which of the following metals would give hydrogen when added to dilute hydrochloric acid. i. Iron, ii. Copper iii. Magnesium
43. Name a non-metallic element, which conducts electricity.
44. Which metals do not corrode easily?
45. What are alloys?
46. Define the following terms.
(i) Minerals
(ii) Ores
(iii) Gangue
47. Name two metals that are found in nature in the free state.
48. What is chemical process used for obtaining a metal from its oxide?
49. Name two metals, which can form hydrides with metals.
50. Does every mineral have a definite and a fixed composition? Explain.
51. Explain the meaning of malleable and ductile.
52. i.Write the electron dot structures for sodium, oxygen and magnesium.
ii. Show the formation of MgO and Na2O by the transfer of electrons.
iii. What are the ions present in these compounds?
53. You must have seen tarnished copper vessels being cleaned with lemon or tamarind juice. Explain why these sour substances are effective in cleaning the vessels.
54. Give an example of a metal which
i. is a liquid at room temperature.
ii. can be easily cut with a knife.
iii. is the best conductor of heat.
iv. is a poor conductor of heat.
55. Why is sodium kept immersed in kerosene?
56. Why do ionic compounds have high melting points?
57. A man went door to door posing as a goldsmith. He promised to bring back the glitter of old and dull gold ornaments. An unsuspecting lady gave a set of gold bangles to him which he dipped in a particular solution. The bangles sparkled like new but their weight was reduced drastically. The lady was upset but after a futile argument the man beat a hasty retreat. Can you play the detective to find out the nature of the solution he had used?
58. Write equations for the reactions of
(i) iron with water
(ii) calcium and potassium with water
59. What would you observe when zinc is added to a sodium of iron(II) sulphate? Write the chemical reaction that takes place?
60. What would you observe when zinc is added to a sodium of iron(II) sulphate? Write the chemical reaction that takes place?
Extra Questions
1. Name the property due to which metals have a shining surface in their pure state.
2. Name a metal which occurs in the free state.
3. Give an example of an elementary substance which is a good conductor of electricity but is not a metal.
4. Name two metals which are both malleable and ductile.
5. Name a non-metal which is lustrous.
6. Name two metals which can be cut with a knife.
7. Name the two metals which do not react with water at all.
8. Name the element which shows non-metallic properties, but is also present in the activity series of metal.
9. If X, Y, Z, W, A, B and C represents the metals in the decreasing order of their reactivity, which metal is most likely to occur in free state in nature?
10. Mention the composition of aqua regia.
11. What is galvanisation?
12. Carat gold is not suitable for making jewellery. Why?
13. How many carats is pure gold?
14. What is an alloy?
15. Why do shopkeepers apply oil on tools made of iron while storing them?
Multiple Choice Questions
1. Which element is used in petroleum jelly ?
a. Sulphur
b. Phosphorus
c. Nirogen
d. Carbon
2. Generally non-metallic oxides are acidic in nature but carbon monoxide is
a. Basic
b. Neutral
c. Amphoteric
d. Doesn't exist
3. Ionic compounds are soluble in water and conduct electricity due to the presence of
a. Free electrons
b. Free ions
c. Free atoms
d. Free molecules
4. Lightest metal is
a. Fluorine
b. Lithium
c. Sodium
d. Hydrogen
5. Coating on galvanised iron is of
a. Cr
b. Sn
c. Hg
d. Zn
6. The metal which occurs in free state is
a. Na
b. Mg
c. Pt
d. Ca
7. The octet rule is not valid for
a. CO2
b. N2
c. O2
d. PCl5
8. The total number of electrons that take part in 'N2' molecule formation is
a. 1
b. 2
c. 6
d. 8
9. Aluminium is very reactive metal but still it reacts slowly with dilute acids due to
a. It's ability to form metallic bond
b. The formation of a tough protective layer of aluminium oxide over it's surface
c. It's oxidising naturec.
d. It's valency
10. Aqua regia is a mixture of
a. Conc. HCl + Conc. H2SO4
b. Conc. HCl + Conc. HNO3
c. Conc. HCl + Conc. HNO3
d. Conc. HCl + Conc. CH3COOH
NCERT Questions
1. Why are unsaturated hydrocarbons more reactive tgan saturated hydrocarbons?
2. How many covalent bonds are there in a molecule of cyclohexane?
3. Give the general formula of paraffins, olefins and alkynes.
4. Why are carbon and it's compounds used as fuel for most applications?
5. Why are carbon compounds not able to conduct electricity through them?
6. Would you able to check if water is hard using a detergent?
7. Explain the formation of scum when hard water is treated with soap?
8. Give a test that can be used to differentiate chemically between butter and cooking oil.
9. An organic compound 'A' is a consituent of antifreeze. The compound on heating with oxygen forms another compound B which has a molecular formula C2H4O2. Identify the compound 'A' and 'B'.write the chemical equation of the reaction that takes place to form the compound 'B'.
10. The molecules of alkene family are represented by a general formula CnH2n.
I. What do n and 2n signify?
II. What is the name of alkene when n=3?
Multiple Choice Questions
Carbon exists in the atmosphere in the form of
(a) carbon monoxide only
(b) carbon monoxide in traces and carbon dioxide
(c) carbon dioxide only
(d) coal
Graphite is used as a lubricant in machines because
(a) it is a good conductor of electricity.
(b) it has a high melting point and slippery layers.
(c) its density ranges from 1.9 to 2.3 g/cm3.
(d) it is strong and soft.
The allotrope of carbon which is a good conductor of heat and electricity is
(a) diamond
(b) graphite
(c) charcoal
(d) none of these
Which of the following is not considered as crystalline allotrope of carbon?
(a) Coal
(b) Diamond
(c) Graphite
(d) Fullerence
Which form of carbon is found in Golkonda mines of Karnataka?
(a) Diamond
(b) Graphite
(c) Coal
(d) Coke
Lead pencil contains
(a) graphite
(b) diamond
(c) lead
(d) lead sulphate
Mineral acids are stronger acids than carboxylic acids because
(i) mineral acids are completely ionised
(ii) carboxylic acids are completely ionised
(iii) mineral acids are partially ionised
(iv) carboxylic acids are partially ionised
(a) (i) and (iv)
(b) (ii) and (iii)
(c) (i) and (ii)
(d) (iii) and (iv)
A few drops of ethanoic acid were added to solid sodium carbonate. The observation made was that
(a) a hissing sound was produced
(b) brown fumes evolved
(c) brisk effervescence occurred
(d) a pungent smelling gas evolved
A reagent which can help us to distinguish between alkenes and alkynes is:
(a) Bromine water
(b) Carbon tetrachloride
(c) Alkaline KMnO4
(d) Ammoniacal cuprous chloride
The soap molecule has a (a) hydrophilic head and a hydrophobic tail
(b) hydrophobic head and a hydrophilic tail
(c) hydrophobic head and a hydrophobic tail
(d) hydrophilic head and a hydrophilic tail
1. Did Dobereiner’s triads also exist in the columns of Newlands’ Octaves ?
Compare and find out.
2. What were the limitations of Dobereiner’s classification ?
3. What were the limitations of Newlands’ law of octaves ?
4. Use Mendeleev’s Periodic Table to predict the formulae for the oxides of the following elements : K, C, Al, Si, Ba
5. Besides gallium, which other elements have since been discovered that were left by Mendeleev in his periodic table ?
6. What were the criteria used by Mendeleev in creating his Periodic Table ?
7. Why do you think the noble gases are placed in a separate group ?
8. How could the modern periodic table remove various anomalies of Mendeleev’s periodic Table ?
9. Name two elements you would expect to show chemical reactions similar to magnesium. What is the basis for your choice ?
10. Name :
(a) three elements that have a single electron in their outermost shells.
(b) two elements that have two electrons in their outermost shells.
(c) three elements with filled outer most shells.
12. (a) Lithium, sodium, potassium are all metals that react with water to liberate hydrogen gas. Is there any similarity in the atoms of these elements ?
(b) Helium is an unreactive gas and neon is a gas of extremely low reactivity. What, if anything, do their atoms have in common ?
13. In the modern periodic table, which are the metals among the first ten elements ?
14. By considering their position in the Periodic Table, which one of the following elements would you expect to have maximum metallic characteristics ?
Ga, Ge, As, Se, Be
15. Which of the following statements is not a correct statement about the trends wlien going from left to right across the periods of Periodic Table.
(a) The elements become less metallic in nature.
(b) The number of valence electrons increases.
(c) The atoms lose their electrons more easily.
(d) The oxides become more acidic.
16. Element X forms a chloride with the formula XCl2, which is solid with a high melting point. X would most likely to be in the same group of the periodic table as
(a) Na
(b) Mg
(c) Al
(d) Si
17. Which element has
(a) two shells, both of which are completely filled with electrons ?
(b) the electronic configuration 2, 8, 2 ?
(c) a total of three shells, with four electrons in its valence shell ?
(d) a total of two shells with three electrons in its valence shell.
(e) twice as many electrons in its second shell as in its first shell ?
18. (a) What property do all elements in the same column of the Periodic Table as boron have in common ?
(b) What property do all elements in the same column of the Periodic Table . as fluorine have in common ?
19. An atom has electronic configuration 2, 8, 7.
(a) What is the atomic number of this element ?
(b) To which of the following elements would it be chemically similar ?
(Atomic numbers are given in parentheses.)
N (7), F (9), P (15), Ar (18)
20. The positions of three elements A, B and C in the periodic table are shown below :
| Group 16 | Group 17 |
|---|---|
| - | - |
| - | A |
| - | - |
| B | C |
(a) State whether A is a metal or non-metal.
(b) State whether C is more reactive or less reactive than A.
(c) Will C be larger or smaller in size than B ?
(d) Which type of ion, cation or anion, will be formed by element A ?
21. Nitrogen (atomic number 7) and phosphorus (atomic number 15) belong to group 15 of the periodic table. Write the electronic configuration of these two elements. Which of these will be more electronegative ? Why ?
22. How does the electronic configuration of an atom relate to its position in the Modern Periodic Table ?
23. In the Modern Periodic Table, calcium (atomic number 20) is surrounded by elements with atomic number 12, 19, 21 and 38. Which of these have physical and chemical properties resembling calcium ?
24. Compare and contrast the arrangement of elements in Mendeleev’s Periodic Table and the Modern Periodic Table.
Extra Questions
1. Phosphorus does not conduct electricity whereas lithium does why?
2. Write general electronic configuration of d-block elements?
3. Why iodine atom is larger in size in comparison to chlorine atom?
4. Why are the group 2 elements called alkaline earth metals?
5. Arrange the following atoms in order of decreasing atomic radius:
Na, Al, P, Cl, Mg
6. What is the atomic number of the element that would occupy, the position in row 7,column 17 of the periodic table?
7. Why are the elements of group 18 called zero valent?
8. If an element X is placed in group 14 , what will be the formula and the nature of bonding of it's chloride?
9. Arrange the ions S2-, Cl−, K+ and Ca2+ in order of decreasing order.
10. Compare and contrast the arrangement of elements of elements in Mendeleev's Periodic Table and Modern Periodic Table.
Multiple Choice Questions
Which one of the following does not increase while moving down the group of the periodic table?
(a) Atomic radius
(b) Metallic character
(c) Valence
(d) Number of shells in an element.
On moving from left to right in a period in the periodic table, the size of the atom
(a) increases
(b) decreases
(c) does not change appreciably
(d) first decreases and then increases.
An atom of an element has the electronic configuration 2, 8, 2. To which group does it belong?
(a) 4th group
(b) 6th group
(c) 3rd group
(d) 2nd group
In modern periodic table, elements are arranged according to their
(a) atomic weight
(b) density
(c) atomic number
(d) melting point
The element with atomic number 14 is hard and forms acidic oxide and a covalent halide. To which of the following categories does the element belong?
(a) Metal
(b) Metalloid
(c) Non-metal
(d) Left-hand side element
The amount of energy released when one or more electrons is added to the neutral atom is
(a) electron affinity
(b) ionisation energy
(c) electron negativity
(d) atomicity
The valence shell of element A contains 3 electrons while the valence shell of element B contains 6 electrons. If A combines with B, the probable chemical formula of the compound is
(a) AB2
(b) A2B
(c) A2B3
(d) A3B2
Arrange the following elements in the order of their increasing non-metallic character.
Li, O, C, Be, F
(a) F < O < C < Be < Li
(b) Li < Be < C < O < F
(c) F < O < C < Be < Li
(d) F < O < Be < C < Li
Which of the following property will be common in group 1 elements?
(a) Mass number
(b) Number of protons in nucleus
(c) Atomic number
(d) Number of valence electrons
Element ‘A’ has electronic configuration 2, 7; ‘B’ has electronic configuration 2, 8, 5 and ‘C’ has electronic configuration 2, 8, 7. Which two elements will exhibit similar chemical properties?
(a) A and C
(b) A and B
(c) B and C
(d) None of these