ICSE CHEMISTRY 8

1.LANGUAGE OF CHEMISTRY

1. Define :
(a) Symbol (b) Valency (c) Radicals (d)Molecular formula (e) Atomic mass (f)Isotopes (g) Chemical equations  (h)Balanced equation (i) Skeletal equations.
2. Give the valencies of the following radicals :
(a) K (b) Al (c) Fe (d) Ag (e)Au (f) Pb  (g) He (h) Ne (i) Mn (j) C (k) O (l) N (m) S (n) Ca
3. Give the symbol and Valencies of the followings :
(a) Hydroxide (b) Acetate (c) Nitrate (d)Bisulphate (e) Bicarbonate  (f) Sulphate (g) Sulphite (h) Dichromate (i) Nitride (j)Phosphate.
4. Why it is necessary to balence a chemical equation?
5. What are the limitations of a chemical equation ?
6. State the law of conservation of mass.
7. Differentiat between
(a) Reactants and Products
(b) A balanced and non balanced chemical equations.
(c) Basic radical and Acid radical.
8. Write the full form of IUPAC.
9. Write the Latin name of the following:
   (a) Fe (b) Na (c) K (d) Cu
10. Write the valence of underlined elements.
  ( a) HCl  (b) H₂O (c) NH₃ (d) CH₄

11. Combining capacity of Helium, Neon and Argon is zero. Why?
12. Define criss cross method.
13. Write the chemical formula of the followings:
(a) Magnesium chloride
(b) Calcium oxide
(c) Zink sulphide
(d) Ammonium chloride
(e) Copper oxide
(f) Iron III chloride
(g) Sodium hydroxide
(h) Iron II sulphide
(i) Lead II nitrate
(j) Nitric acid
(k) Sulphuric acid
(l) Calcium hydroxide
(m) Magnesium carbonate
(n) Ammonium carbonate
(o) Sulphur trioxide.
(p) Baking soda
(q) Common salt.
Find the number and names of elements present in them and calculate their molecular mass.
14. What information do you get from the formula.
(a) SO₂  (b) NH₃
15. We cannot write the equation as   H + Cl = HCl. Why?
16. Write the balanced chemical equations for the following:
(a)Burning of magnesium in the presence of oxygen
(b)Reaction of hydrogen with oxygen to produce water.
(c)Reaction of Iron II with hydrochloric acid.
(d)Reaction of Zinc with sulphuric acid.
(e) Reaction of iron with chlorine
(f) Reaction of magnesium with dilute sulphuric acid.
(g) Reaction of calcium oxide with water (h)Reaction of sodium with chlorine
17. How can a chemical equation be more informative?
18.Write the valency of the elements in the followings:
(a) Aluminium chloride
(b) Aluminium oxide
(c) Aluminium Nitride
(d) Aluminium Sulphate
19.What is the variable valence? Give give examples of element sowing variable valence.
20. What information is conveyed by the formula H₂O ?
21. State the limitations of a chemical equation.
22. Write the names of the following compounds.
 (i) Al₂(SO₄)₃ (ii) (NH₄)₂(SO₄) (iii) KClO₃ (iv) KClO
 (v) Pb(NO₃)₂ (vi)Mg(HCO₃)₂ (vii) KMnO₄(viii) PbCO₃
 (ix) PbO₂ (x)Fe(OH)₃.
23.Write the formulae of the following acids.
 (i) Carbonic acid
(ii) Sulphurous acid
(iii) Nitrous acid
 (iv) Phosphoric acid
(v) Hydrochloric acid
(vi) Nitric acid
(vii) Sulphuric acid
24. What do the following symbols denote?
 (i) 2H (ii) H2 (iii) H+
25.  Balance the following equations :
 (2) NaNO₃  →NaNO₂+ O₂
 (3) Ca +H₂O → Ca(HO)₂ + H₂
 (4) NaNO₃+H₂SO₄→Na₂SO₄ + HNO₃
 (5) Na₂CO₃+H₂O + CO₂→ NaHCO₃
 (6) Mg + HCl ⎯⎯→ Mg Cl₂ + H₂
(7) Na +H₂O ⎯⎯→ NaOH + H₂
 (8) C₄H₁₀+O₂⎯⎯→ CO₂ +H₂O
 (9) FeS + HCl ⎯⎯→ FeCl₂ +H₂S
 (12) NH₃+ O₂ ⎯⎯→N₂ +H₂O
 (13) MgCl₃+ Na₂CO₃⎯⎯→ NaCl + MgCO₃
 (14) NaOH +Cl₂⎯⎯→ NaCl + NaClO +H₂O
 (15) FeCl₃+ NaOH ⎯⎯→ NaCl + Fe(OH)₃
 (17) KNO₃+H₂SO₄⎯⎯→K₂SO₄ + HNO₃
 (18) PbO + HNO₃⎯⎯→ Pb(NO₃)₂+H₂O
 (19) FeSO₄+ NaOH ⎯⎯→Na₂SO₄+ Fe(OH)₂
 (2) 2NaNO₃→ 2NaNO₂+ O₂

2. MATTER

1.Define
(a) Matter (b) Inter molecular force of attraction (c) Atom (d) Molecules (e) Fluid
2.What are three states of matter? Define each of them with two examples of each.
3.Define inter conversion of states of matter.What are the two factors responsible for the change of state of matter?
4. Define kinetic theory of matter .State the main postulates of kinetic theory of matter.
5. What happens to water
(a) if it is kept in a deep freezer
(b) if it is heated?
 Explain the phenomenon of change of state of water.
6.(a)State the law of conservation of mass.
(b) What do you observe when Barium Chloride solution is mixed with Sodium sulphate solution?
(c) What do you observe when Sodium bicarbonate mixed with vinegar?
7.Give reason:
(a) A gas can feel the whole vessel in which it is enclosed solids.
(b) Solid cannot be compressed
(c) Liquid can flow.
(d) When magnesium is burnt in air, there is an increase in mass after the reaction.
(e) When wood is burnt in air, ash is formed and the mass of ash less than wood. Why?
(f) To prove the law of conservation of mass, it is necessary to carry out the experiment in a closed container. Why?
8. Write three examples to explain  the change of state of matter by changing the pressure.
9.Give two examples for each of the following:
(a) The substances which sublime.
(b) The substances which do not change their state on heating.
10.Write the differences of properties bases on kinetic theory, between solid liquid and gases.
11.How and why do the changes takes place in matter?
12. Fill in the blanks:
(a) The change of a solid into a liquid is called .................
(b) The process in which a solid directly changes into a gas is called...........
(c) The change of water vapour into water is called
(d) The temperature at which a liquid starts changing into its vapour state is...............
(e) A drop of water contains..........particles of water.
(f) When sodium carbonate react with acetic acid a strong effervescence or fizz sound is produced which indicates formation of ....................
13. State the main postulates of kinetic theory of matter.

 CHEMICAL REACTION

1.Define
(a) Chemical reaction (b) Chemical bond  (c)  Effervescence  (d)  Precipitates  (e) Exothermic reaction (f) Endothermic reaction  (g)  Photosynthesis  (h) Promoters  (i)  Indicators  (j)  Amphoteric Oxide
2. Give three examples of each which illustrates the following characteristics of a .chemical reaction:
(a) Evolution of gas  (b) Change of colour (c) Change in state  (d)  Formation of precipitation  (e) Exothermic reaction  (f)  Endothermic reaction.
3. How do the following help in bringing about a chemical change?
(a) Pressure  (b) Light  (c) Heat  (d) Catalyst  (e)  Electricity  (f)  Close contact  (g)  Mixed in solution.
4. Define catalyst. What are positive catalysts and negative catalysts ? Explain with example.
5. What do observe when :
(i) Dilute sulphuric acid is added to zinc granules. (ii) A piece of iron is dipped in a blue solution of copper sulphate. (iii) A silver nitrate is added to a solution of sodium chloride ?  (iv) Ferrous sulphate solution is added to an aqueous solution of sodium hydroxide. (v) Solid lead nitrate is heated.
(vi)  Calcium bicarbonate is heated. (vii) Potassium chlorate is heated (viii) Sodium sulphite is added to hydrochloric acid.
6. Why are sodium and potassium kept in kerosene ?
7. Write an example of promoter.
8. What is bio chemical catalyst ? Write the name position and functions of biochemical catalyst.
9.What are the different types of chemical reaction? Explain with two chemical reactions.
10. How will you obtain:
(i) Magnesium oxidefrom magnesium
(ii) silver chloride from silver nitrate
(iii) nitrogen dioxide from lead nitrate
(iv) zinc chloride from zinc
(v) ammonia from nitrogen
 Also give balanced equations for the reaction.
11.What do you observe
(i) When iron nail is kept in copper sulphate solution for sometime
(ii) Phenolphthalein is added to sodium hydroxide solution
(iii) Blue litmus paper is dipped in dilute hydrochloric acid
(iv) Lead nitrate is heated
(v) Magnesium ribbon is burned in oxygen
(vi) Ammonium is brought in contact of hydrogen chloride gas.
12. Give reason
(i) A person suffering from acidity is advised to take an antacid.
(ii) Acidic soil is stated with quicklime.
(iii) Wasp sting is treated with vinegar.
(iv) What is meant by the metal reactivity series ? What are its important features ?
(v) What are oxides?  Give two examples of each of the following oxides.
(i)  Basic oxide (ii) Acidic oxide (iii) Amphoteric oxide (iv) Neutral oxide.
13. Define alkalis. All alkalis are bases but all bases are not alkalis . Explain it.
14. (i) How can you show that iron is more reactive than copper.
(ii) How can you show that copper is more reactive than silver
15. Classify the following reactions as combination, decomposition, displacement,  precipitation and neutralization. Also balance the equations.
(i) CaCO₃ (s)⎯⎯→CaO(s) + CO₃(g)
(ii) Zn(s) + H₂SO₄  (l)⎯→ZnSO₄ (s) + H₂(g)
(iii) Ag(NO₃) (aq)+ NaCl(aq) ⎯⎯→NaNO₃ (s) + AgCl(s)
(iv) NH₃ (g)+ HCl (g) ⎯⎯→NH₄Cl(s)
(v) CuSO₄ (aq) +  H₂S(g) ⎯⎯→CuS(s) + H₂SO₄(l)
(vi) Zn(s) + CuSO₄(aq) ⎯⎯→ZnSO₄(aq)+ Cu(s)
(vii) Ca(s) + O₂(g) ⎯⎯→CaO (s)
(viii) KOH + H₂SO₄ .⎯⎯→K₂SO₄. + H₂O
16. Write the missing reactants and product and balance the equations:
(i) PbO +.........⎯→Pb + H₂O    (ii)  NaOH +............⎯→ NaCl +..........
(iii) KClO₃ (Heat).⎯→ ...........+ ............  (iv) ...........  + HCl ⎯→ NaCl + H₂O.
16. What happens when
(a) Acidic oxide react with base and alkali. (b) Non metal is heated with oxygen .
(c) Non metallic oxide react with water. (d) Basic oxide react with acid .
(e) Amphoteric oxide react with acid and base . (f) Basic oxide dissolve in water.
(g) Metal reacts with oxygen.
17. What are the importance of neutralization reaction in (i) Indigestion (ii) Insect sting (iii) Soil treatment.
18. Write the colour of the following indicator in acid and base. (i) Litmus  (ii) Methyle orange
(iii) Phenolpthalein.
19. When lead nitrate is heated, a brown fumes is evolved. Write the name of this fumes.
20. Write the function of enzymes present in (i) yeast cell maltase and zymase.(ii) body cells Amylase, pepsin, trypsin and lypase.

3. ELEMENT COMPOUND AND MIXTURE

1. Fill in the blank spaces with the appropriate words given within the brackets.
 (a) A pure chemical compound is ______________
 (homogenous/heterogenuos) in nature.
 (b) Constituents of a mixture can be separated by employing suitable
 ______ (chemical/physical) means.
 (c) The clear liquid obtained from a mixture of an ______
 (soluble/insoluble) solid and a liquid by the process of ______
 (filtration/decantation) is called filtrate.
 (d) The process of separation of different dissolved constituents of a
 mixture by adsorbing them over an appropriate ________
 (adsorbent/absorbent) material is called ________
 (filtration/chromatography).
 (e) A mixture of iodine and sand can be separated by the process of
 _______ (decantation/sublimation).
(f)______ is the most abundent element present in earth's crust.
(g) _______ element has highest percentage of in air.
(h) ______ and ______ are the two soft metals.
(i) ________ is a liquid metal and _______ is a liquid non metal.
(j) _______ metal is brittle.
(k) _____ metal is lustrous and good conductor of electricity.
(l) Carbon dioxide is formed from carbon and oxygen with _________ heat while nitric oxide is formed from nitrogen and oxygen with the ______ of heat energy.
(m) The hardest naturally occurring substance is __________.

2. Match the statements in Column A, with the statements in Column B.
Column A Column B
(a) The process of removing coloured dyes from blue black ink.       Sedimentation
(b) The process of removing common salt from its aq. solution       Fractional Distillation
(c) The process of obtaining drinking water from sea.                        Crystallisation
(d)The process of removing suspended particles from river water.    Chromatography
 3. Statements given below are incorrect. Write the correct statements.
 (a) The number of atoms present in one molecule of a compound is called
atomicity.
 (b) The symbol for element sodium is SO.
 (c) The constituents of a mixture are present in a fixed ratio.
 (d) The insoluble material which settles down, when a suspension is allowed
 to stand undisturbed is called a filtrate.
 (e) Alcohol is separated from its solution in water, because there is very
 little difference in their boiling points.
 4. (a) Define pure substance and /impure substance
 (b) State three characteristics of a pure substance and impure substance.
 (c) Pick out the pure substances from the following list :
 (i) Sugar solution (ii)Common salt crystals
 (iii) Milk (iv)Lead nitrate crystals
 (v) Brass (vi)Distilled water
 (vii) Lime stone (viii)Petrol
 (ix) Ammonium nitrate (x) Honey.
Or write the differences between pure and impure substances.
5. Define element. State three characteristics of element.
6. What is the total no. of elements at present and how many elements are natural and artificial ?
 7.Define metal and nonmetal by giving two examples.
 (a) State four characteristics of metals.
 (b) State four characteristics of non-metals.
 8. By giving five examples each, define :
 (i) Metalloids (ii) Noble gases.
 9. (a) Name two metals which cannot be kept in air or water.
 (b) Name a non-metal which is kept under water.
 (c) Name two metals which are in the liquid state at room
 temperature (20 °C).
 (d) Name a non-metal which is a good conductor of electricity.
 (e) Name two metals which offer very large resistance to the passage of
 electric current.
 (f) Name an inert gas heavier than air and is given out by the earth.
 (g) Name a non-metal lighter than air.
 (h) Name a non-metal which is in the liquid state at room temperature.
 (i) Name two non-metals which dissolve in carbon disulphide.
 (j) Name two elements present in stars.
 (k)Name three most common elements present in the human body.
 (l) Name a non-metal having lustre.
 (m) Name three elements which are attracted by a magnet.
 10. (a) What do you understand by the term compound?
 (b) State four characteristics of a chemical compound.
 (c) How is Sodium Chloride different from its constituent elements ?
(d) Why is iron sulphide a compound?
11. Write the methods of separation of mixture with examples.
 12. (a) What do you understand by the term mixture?
 (b) State four characteristics of a mixture.
 13. State four differences between (a) chemical compound and a mixture(b) Homogeneous and heterogeneous mixture.
 14. “Water is a chemical compound”. State three reasons to prove the correctness
 of the statement.
 15. "Air is a mixture". Is this statement correct? Give three reasons in support of
 your answer.
 16. Milk is regarded as a mixture and not a pure substance. Give one reason.
 17. Sugar is regarded as a pure substance, but not a mixture. Give one reason.
 18. Wax is regarded as a mixture and not a pure substance. Give one reason.
19. Classify the following into elements, mixtures and compounds.
 (1) Distilled water (2) Mercury (3) Glass (4) Ammonia gas (5) Honey (6) Gold (7) Milk (8) Rain water (9) Oxygen (10) Common salt (11) Diamond (12) Soap (13) Cooking gas (14) Ice-cream
 (15) Graphite  (16) Silver (17)Fruit juice (18) Sea water (19) Apple juice (20) Alcohol (21) Sulphur
 (22) Carbon dioxide (23) Sugar (24) Lime stone (25) Dry ice (26) Washing soda (27) Kerosene oil (28) Wax (29) Rust (30) Hydrogen.(31) Blood (32) Iron sulphide.
 20. Give three examples of each of the following types of mixture with homogeneous and heterogeneous mixture.
 (i) Solid + solid (ii) Solid + liquid (iii) Solid + gas (iv) Liquid + liquid (v) Liquid + gas
(vi) gas in gas.
 21. (a) Define : (i) Filtration (ii) Filtrate.
 (b) Why common salt cannot be filtered from common salt solution?
22. (a) Define :
 (i) Sedimentation (ii) Sediment
 (iii) Supernatant liquid (iv) Decantation.
 (b) Name a suspension which can be separated by decantation.
 23. Define the following terms :
 (1) Evaporation (2) Distillation (3) Fractional distillation
 (4) Crystallization (5) Chromatography.
 24. Name the process or processes used to separate the following mixtures.
(1) Coloured dyes from black ink.
(5) Petrol from a mixture of petrol and mobil oil.
(6) Common salt from its salt solution.
(7) Suspended particles from river water.
(8) Drinking water from sea water.
(9) Iron from a mixture of iron fillings and sand.
(12)Petrol from a mixture of petrol and water.
 25.(a) What is the principle of chromatography? (b)Write two common absorbents and four common solvents.(c) Write four advantages of chromatography.
 26. Complete the table given below based on separation techniques. The first has
 been done as an example.
Mixture                         Type of Mixture             Separation Technique           Principle involved
1. Oxygen+ nitrogen     Heterogeneous               Fractional  evaporation       Difference in boiling
                                                                             of liquefied mixture.                      points.                                                         
2. Sand + water
3. Saw dust + water
4. Iron + sulpher
5. Kerosene oil + water
6. Common Salt + potassium nitrate
7. Colours of blue black ink.
8. Chalk powder + water
9. Clay +Water
10.Tea + Tea leaves
11.Sodium chloride + calcium carbonate
12.Common Salt + ammonium chloride
13. Alcohol + water
14 mixture of gas in liquid
15.Ammonium chloride + sand
16. Calcium carbonate + sodium chloride
 27. Why is it necessary to separate the constituent of a mixture?
 28. How will you obtain pure iodine from a sample of impure iodine?
 29. Describe briefly how will you remove grease stains from warm clothes?
 30. Describe briefly how will you obtain pure water from sea water?
 31. How will you obtain a pure sample of iodine from a mixture of iodine and
 ammonium chloride, without heating?

 32. From the techniques (methods) of distillation, filtration , fractional distillation,
 chromatography, electrolysis, crystallization select and write down the
 techniques you would use to separate :
 (i) Constituents of colouring matter in ink.
 (ii) Hydrated copper sulphate from its aqueous solution.
 (iii) Pure copper from a sample of impure copper.
 (iv) Nitrogen gas from liquid air.
 (v) Unused zinc after reaction of excess of zinc with dilute sulphuric acid.
 34. State two advantages of chromatography over the other methods of separation.
 35. (a) What is centrifugation?
 (b) What kind of (solution / suspension) is separated by centrifugation?
 (c) What is the principle of centrifugation?
 36. State four applications of centrifugation technique.
37. Name the formula of  (a) Common salt (b) Glucose (c) Backing soda (d) Marble (e) Sand
38 Define residue.
39.Different between miscible and immiscible liquids.
40. Name a mixture whose constituents can be conveniently separated from
 each other by :
 (i) Fractional distillation (ii) Fractional crystallisation.
 (iii) Sublimation (iv)Evaporation
 (v) Filtration (vi)Liquefaction

 (vii) Chromatography (viii) Diffusion.