Very Short Answers Question:-
Q1. Why are metals good conductors of electricity?
Ans:- Metals are the good conductor of electricity because these metals contain free electrons that can move easily and hence help in the conduction of Electricity.
Q2. Which property of graphite is utilized in making electrodes?
Ans:- Graphite is utilized in making electrodes because this is a good Conductor of Electricity. And also this is a very stable carbon compound and does not show reaction with the different metal salts.
Q3. Name two metals that do not react with water at all?
Ans:- Gold and Platinium, are the two metals that do not react with the water at all.
Q4. What will happen when calcium is treated with water?
Ans:- When calcium is treated with the water then a vigorous exothermic reaction will take place. And the formation of H2 (g) will also take place.
Ca + H2O —–> CaO + H2
Q5. What is the nature of non Metal oxides?
Ans:- Generally, non- Metal oxides are Acidic in nature.
Q6. What is the nature of metal Oxide?
Ans:- Generally, Metal oxides are basic in nature.
Q7. why does calcium floats in water?
Ans:- Calcium Starts floating in water because when it reacts with the water then bubbles of Hydrogen gas release and these bubbles stick at the surface of calcium which causes the Calcium to float on the surface of the water.
Q8. What is the flux?
Ans:- It is a substance that is added to the ore, during reduction, for removing the non-fusible Impurities, is known as Flux.
Q9. Why do silver Articles become black in color when left in air for a long time?
Ans:- Sulphur compounds such as hydrogen sulfide gas (H2S) present in the air when combines with the silver article, from a black coating of silver sulfide.
Q10. Why are Ionic compounds usually hard in nature?
Ans:- IN all Ionic compounds, their positive and negative ions are attached to each other by a strong ionic bond. So they are rigid and hard solid.
Q11. What is corrosion?
Ans:- When the surface of metal attacked by air, water, and some other substances, it is said to be corroded. This phenomenon is known as corrosion.
Q12. What is Rust?
Ans:- The Coating of brown, flaky substance on the surface of Iron corrodes when it kept exposed in moist air is called rust.
Q13. What Is Aqua Regia?
Ans:- It is a freshly prepared mixture of concentrated hydrochloric acid and concentrated hydrochloric acid and concentrated nitric acid in the ration of 3:1. it can dissolve gold. It is highly corrosive Liquid.
Q14. What is galvination?
Ans:- Galvanisation is a method of protecting steel and iron from rusting by coating them with Zinc.
Q15. Why aluminum cannot be obtained by the reduction of its oxide with Carbon?
Ans:- Because Aluminum has more affinity for oxygen than carbon.
Q16. Why is stainless steel preferred in making household Utensils?
Ans:- Stainless steel is preferred as it is non-reactive and so milk the milk or food is not spoiled in it.
Short Questions/Answer-I [2-Marks]
Q1. Explain why the surface of some metals acquires a dull appearance when exposed to air for a long time?
Ans:- The Surface of some metals acquires a dull appearance when exposed to air for a long time due to the formation of a thin layer of oxide, carbonate or sulfide on their surface by the slow action of the various gases present in the air.
Q2. What happens when
(i). Iron nail is placed in silver Nitrate solution?
(ii). Iron Strip is dipped in a zinc sulfate solution.?
Ans:- (i). Iron is most reactive than Silver. Fe(s) + 2AgNO3(aq) ——-> Fe(NO3)2 (aq) + 2Ag(s).
(ii). Iron is below zinc in the reactivity series. Therefore, Iron cannot displace zinc from zinc sulfate solution. No reaction takes place.
Q3. Why do metals evolve hydrogen gas when reacts with the Nitric Acid?
Ans:- When metals react with nitric acid (HNO3), hydrogen gas is not evolved. This is because HNO3 is a strong oxidizing agent. It oxidizes H2 produces to water and is itself reduced to any of the oxides of nitrogen (N2O, NO or NO2). For example, 3Cu + 8HNO3 —-> 2NO + 3Cu(NO3) (aq) + 4H2O.
Q4. List any two observations when a highly reactive metal is dipped in water?
Ans:- (i). A large amount of heat is evolved.
(ii). Metals start floating.
Q5. What is 24-carat of gold? How will you convert it into 18-carat?
Ans:- 24-carat gold is pure gold. Pure gold is very soft and not suitable for making jewelry. Therefore, to increase its hardness, it is alloyed either with copper or silver. 18-carat gold is prepared by alloying 18 parts pure gold with 6 parts of either copper or silver.
Q6. Why is aluminum oxide considered an amphoteric oxide?
Ans:- Aluminium oxide (Al2O3) shows basis as well as acidic behavior because it reacts with both acids and bases. Thus, it is considered as an amphoteric oxide. The two types of reaction given by Al2O3 follow:
(i). Al2O3 (s) + 6HCl (aq) —–> 2alCl3(aq) + 3H2O(l), In this reaction, Al2O3 behaves as a basic oxide because it reacts with an acid to form salt and water.
(ii). Al2O3 + 2NaOH(aq) ——–> 2NaAlO2 + H2O, In this reaction, al2O3 behaves like an acidic oxide in nature because it reacts with the base to form salt and water.
Q7. Why are food cans tin-plated instead of zinc plated though zinc is cheaper than tin?
Ans:- Tin is less reactive than zinc. It is less likely to dissolve in the liquid stored in the food cans. Tin reacts only powerful acids whereas zinc can easily react even with tomatoes, so it is not safe to store food in zinc-plated cans.
Short Question/Answer-II [3-Marks]
Q1. Name two metals that react violently with cold water. Write any observations you would make when such a metal is dropped into water. How would you Identify the gas evolved, if any, during the reactions?
Ans:- Metals that react violently with cold water are potassium (K) and sodium (Na).
2K + H2O ——> 2KOH + H2 + heat energy
2Na + 2H2O ——–> 2NaOH + H2 + heat energy
The hydrogen gas produced during the reactions of these two metals with water Immediately catches fire. Thus, these reactions are violent and exothermic.
The gas evolved during these reactions burns with a popping sound which confirms that the gas is Hydrogen (H2).
Q2. Explain the following statements:-
(i). Most metal oxides are insoluble in water but some of these dissolve in water. What are these oxides and their solutions in water called?
(ii). At ordinary temperature, the surface of metals such as magnesium, Aluminimum, and zinc, etc. is covered with a thin layer. What is the composition of this layer? state its importance.
(iii). Some alkali metals can be cut with a knife.
Ans:- (i). These oxides are called basic and their solutions in water are called alkalis.
(ii). This layer formed is a protective oxide layer that prevents the metal from further oxidation.
(iii). some Alkali metals can be cut with a knife because they are very soft and have low densities.
Q3. Give Reasons:-
(i). Platinum, Gold, and silver are used in making Jewellery.
(ii). Sodium, Potassium, and lithium are stored under oil.
(iii). Aluminum is a highly reactive metal, yet it is used in making the utensils for cooking?
Ans:- platinum, Gold and silver are used to make jewelry because of their bright shiny surface and high resistance to corrosion. Also, they have high, malleability and Ductility.
(b). Sodium, potassium, and lithium are stored under oil to prevent their reaction with oxygen, moisture and carbon dioxide of air so as to protect them as highly reactive metal.
(c). Aluminum metal forms a thin layer of aluminum oxide all over its surface under the action of moist air. This layer prevents the metal underneath from further corrosion. It is cheap, easily available, malleable and ductile. Therefore, It is used to make utensils for cooking.
Q4. What is the difference between the Roasting and Calcination?
Ans:- The ore in heating produces sulfur dioxide gas so it is sulfide ore. The method used for its concentration is the “Forth floating process”. After the concentration of the ore following two steps would be followed to convert it into metal.
(i). Roasting:- The Sulphide ore is converted into its oxide by heating in the presence of air. MS + O2 ——-> MO + SO2.
(ii). Reduction of Metal-oxide to Metal:- the oxide formed by roasting is then reduced to metal by using a suitable reducing agent like carbon (coke). MO + C ——> M + CO.
Q5. Explain how the properties of an alloy are different from those of constituents metals?
Ans:- (i). Alloys are stronger and harder than the constituent Metals.
(ii). Alloys are more resistant to corrosion.
(iii). Alloys have a lower melting point than the constituent Metals.
(iv). Alloys have lower electrical conductivity than pure metals.
Q6. Which two metals do not corrode easily? Give an example in each case to support the
(i). Corrosion of some metals is an advantage.
(ii). Corrosion of some metals is a serious problem.
Ans:- Gold and Platinium.
(i). a thin aluminum layer of aluminum oxide forms a protective layer that protects aluminum metals underneath from further damage.
(ii). Corrosion of Iron is a serious problem. Every year an enormous amount of money is spent to replace damaged iron and steel structure.
Q7. How can a layer of aluminum oxide on an object be made thicker? what is this process called?
Ans:- Aluminium develops a thin layer when exposed in the air. This Aluminium oxide coat makes it resistant to further corrosion. The resistance can be improved further by making the oxide layer thicker. This process is called anodizing.
During anodizing, a clean aluminum article is made the anode and is electrolyzed with dilute sulphuric acid. The oxygen gas evolved at the anode reacts with aluminum articles an attractive finish.
Long Questions/Answer:- [5-Marks]
Q1. What are Ionic or Electrovalent Compounds? Give an Example of Ionic Compound. Explain with reason four properties of these compounds.
Ans:- ionic Compounds are those compounds which are formed by the transfer of electrons from a metal to a non-metal. For Example, NaCl.
(i). Physical properties:- Ionic Compounds are hard and solid due to the strong force of attraction between oppositely charged ions.
(ii). Melting point and Boiling point:- As the amount of energy is required to break strong bonds. So they have a high melting point and boiling point.
(iii). Solubility:- These are soluble in water (polar solvent) but insoluble in an organic solvent.
(iv). Conduction of electricity:- They conduct electricity in solution or molten state as ions move towards opposite electrodes.
Q2. (i) Hydrogen is not a metal but it has been assigned da [place in the reactivity series of metals? Explain.
(ii) How would you show that silver is chemically less reactive than copper?
Ans:- Though Hydrogen is not a metal even then it has been assigned a place in the reactivity series. The reason is that like metals, hydrogen also has a tendency to lose electrons and form a positive ions H+.
The metals which lose electrons less readily than hydrogen are placed below it and the, metals that lose electrons more readily than hydrogen are placed above in the reactivity series of the metals.
(ii). By Displacement Reaction silver can be shown to be chemically less reactive than copper or copper is more reactive than silver. If a piece of silver is immersed in a solution of copper sulfate solution.
CuSO4 + Ag —–> No Reaction.
On the other hand, If a copper plate is placed in a solution of silver nitrate, copper will slowly displace silver from the solution and blue solution of copper nitrate is formed.
2AgNO3(aq) + Cu (s) —-> Cu(NO3)2 (aq) + 2Ag(s), This shows that copper is more reactive than silver.
Q3. (i). What is an Ionic Bond?
(ii). How is an Ionic Bond formed?
Ans:- The chemical formed by the transfer of electrons from one atom to another is known as an ionic bond.
(ii). An Ionic bond is formed when one of the atoms can donate electrons to achieve the inert gas electronic configuration and other atom needs electrons to achieve the inert gas electronic Configuration.
When a metal (usually 1,2 or 3 electrons in the outermost shell) reacts with a non-metal (Usually5,6 or 7 electrons in the outermost shell), the transfer of electrons takes place from the metal atom to the non-metal atoms and anatomic and an ionic bond is formed. There is a strong force of attraction of electrostatics attraction between metallic cation and a non-metallic anion which is responsible for the formation of Ionic Bond.
Q4. Give Reasons:-
(i). Reactivity of Al decreases if it is dipped in HNO3.
(ii). Carbon cannot reduce the oxide of Na or Mg.
(iii). NaCl is not a conductor of electricity in the solid-state whereas it does not conduct electricity in aqueous solution as well as in Molten state.
(iv). iron Articles are galvanized.
(v). Metals like Na, K, Ca and Mg are never found in their free state in nature.
Ans:- Due to the formation of a layered oxide, i.e., Al2O3 it becomes less reactive.
(ii). Na or Mg is the most reactive metals as compared to carbon. So their oxides are most stable.
(iii). In solid NaCl, The movement of ions is not possible due to its rigid rigid structure but in aqueous solution or molten state, the ions can move freely. These free ions are responsible for the conduction of electricity.
(iv). Iron articles are galvanized to protect them from corrosion.
(v). Na, K, Ca, and Mg are highly reactive metals and thus never found in their free state in nature.
HOTS (Higher order thinking Skills)
Q1. There are 3 unknown metals– A, B and C. C displace B from its oxide while with oxide of A, there is no displacement reaction. Give the Reactivity order of A,b and C.
Ans:- C displaces b from its oxide, therefore, C is more reactive than B.
There is no reaction when C is treated with the oxide of A or C does not displace A from its oxide. So, A is more reactive than C. Thus the reactivity order is B<C<A.
Q2. A copper Coin is kept Immersed in a solution of silver nitrate for some time. What will happen to the coin and the color of the solution?
Ans:- Copper is placed above the silver in the reactivity series which indicates that copper is more reactive than the silver, when a cop[per coin or strip is kept immersed in a solution of silver nitrate.
2AgNO3 (aq) + Cu (s) ——-> Cu(NO3)2 (aq)
Copper slowly displaces silver form the AgNO3 solution and the color of solution changes from colorless to blue dur to the formation of copper nitrate [Cu(NO3)2]. The copper coin will disappear and silver will precipitate out.
Q3. Carbon can reduce copper oxide to copper but not CaO to Ca. Why?
Ans:_ C us strong reducing and can reduce CuO as follows:-
CuO + C —–> Cu + CO
ca is much more reactive than Cu and has a greater affinity for oxygen than C has. So, Carbon cannot reduce CaO to Ca.
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