Question-2. Explain the meaning of malleable and ductile.

Ans-

Traumatic:- Some metals can be beaten into thin sheets. This property of metals is called malleable. Gold and silver are the most malleable. 0.0004 mm thin sheet can be made by beating gold.

Tensile:- Some metals can be drawn in the form of a thin wire. This property of metals is called ductility. Silver is the most ductile metal.

Question-3. Why does the surface of metals become hazy or the luster of the metal decreases?

Ans- Metals lose their luster when exposed to air (air) for a long period of time as they react with the constituents of air, oxygen, CO, water, etc. to form oxides, carbonates, sulfides, etc. Due to which their layer gets deposited on the metals. Hence the surface of metals becomes blurred.

Question-4. Who is Acoustic?

Ans- When metals strike a hard surface, they produce a special type of sound. Therefore, this special sound produced in metals is called acoustic.

Question-5. Why do metals form positive ions?

Ans- Metals have 1, 2 or 3 electrons in their outer shell, due to which metals readily give up electrons to form electropositive ions.

Question-6. What happens when metals are combusted in air?

Ans- When metals are combusted in air, they combine with oxygen to form metal oxides. These metal oxides are basic because they turn red litmus paper soaked in water blue. These oxides of metals are soluble in water.

Metal + Oxygen → Metal Oxide

2Mg + O₂ → 2MgO

Question-7. Why is sodium, potassium or lithium kept immersed in kerosene oil?

Ans- When sodium, potassium or lithium is left open in the air, it reacts with oxygen and automatically catches fire (at about 23 °C) i.e. starts burning. Therefore, to keep it safe, it is kept immersed in kerosene oil because it does not react with kerosene oil and does not dissolve in it.

Question-8. What is amphoteric oxide, and what is anodization?

Ans-

Amphoteric oxide:- Some metal oxides are both acidic and basic in nature, such metal oxides are called amphoteric oxides. Eg:- aluminum oxide (Al₂O₃), zinc oxide (ZnO)

Anodization:- The process of forming a thick oxide layer on aluminum is called anodization.

Question-9. What happens when metals react with water?

Ans-

Reaction with cold and hot water:- When a metal reacts with cold or hot water, it forms metal hydroxide and hydrogen gas.

2K + 2H₂O (cold water) → 2KOH + H₂ (thermal energy)

Mg + 2H₂O (hot water) → Mg(OH)₂ + H₂

Reaction with steam:- When metals react with steam, they form metal oxides and hydrogen gas.

2Al + 3H₂O → Al₂O₃ + 3H₂

Question-10. Copper is used to make hot water tanks, but steel is not. Why?

Ans- Copper does not react with water under any circumstances, but iron reacts with steam of boiling water to form oxides and hydrogen gas. Therefore, copper is used in making hot water tanks but steel is not.

Question-11. What happens when metals react with acids?

Ans- Metals react with acids to form salts and hydrogen gas.

metal + acid → salt + hydrogen gas

Mg + 2Hcl → Mgcl₂ + H₂

Question-12. What is Aquaregia?

Ans- A fresh mixture of concentrated hydrochloric acid and concentrated nitric acid in the ratio 3:1 is called aquaregia. It is a flammable liquid. It can also dissolve gold and platinum. When old and dirty gold jewelery is dipped in aquaregia solution, it shines like new jewelry.

Question-13. What is Activity Category?

Ans- On the basis of displacement reaction, metals are arranged in order of their decreasing reactivity, which is called activity series of metals. In this, the most reactive metal is on top and the least reactive metal is at the bottom.

Question-14. Which metals are found in combined state in nature?

Ans- The metals which are most reactive are found in the combined state in nature.

Ex:- Lithium, potassium, sodium, calcium.

The metals which are less reactive are found in free state in nature.

Ex:- Platinum, Gold, Silver (Silver), Mercury (Mercury), Copper.

Question-15. Why is hydrogen not given a place in the activity series even though it is a non-metal?

Ans- Like metals, hydrogen also loses electrons and forms positive ions. Therefore, despite being a non-metal, hydrogen has not been given a place in the activity series.

Question-16. Why are non-metals electrically negative?

Ans- Atoms of nonmetals (except hydrogen and helium) have 4, 5, 6, 7 electrons in their outermost shells. Therefore, non-metals take electrons to form negatively charged ions. Hence non-metals are electronegative.

Question-17. What do nonmetals react with oxygen to form?

Ans-

Non-metals react with oxygen to form acidic oxides.

S + O₂ → SO₂ (acidic)

Some non-metals react with oxygen to form neutral oxides.

2H₂ + O₂ → 2H₂O (indifferent)

Question-18. Differentiate between metals and non-metals on the basis of physical properties?

Ans- On the basis of physical properties, there are following differences between metals and non-metals-

Question-19. Find out the difference between metals and non-metals on the basis of chemical properties?

Ans- On the basis of chemical properties, there are following differences between metals and non-metals—

Question-20. Why do noble gases not take part in the reaction?

Ans- Helium, neon and argon are noble gases. The outermost shells of these gases are full. Hence it does not participate in the reaction.

Question-21. What are ionic compounds or electrovalent compounds called? What are the properties of ionic compounds?

Ans- Compounds formed by the transfer of electrons from metal to non-metal are called ionic compounds or electrovalent compounds.

Ionic compounds have properties—

• Ionic compounds are solid and hard.

• Ionic compounds have high melting and boiling points.

• Ionic compounds are soluble in water.

• In the solid state, ionic compounds do not conduct electricity, that is, they are poor conductors of electricity.

• Ionic compounds conduct electricity in aqueous solution or molten state.

Question-22. In how many states are metals found in nature?

Ans- Metals are found in nature in two states—

1. free state:- The metals which are least reactive are found in free state. Eg:- Gold, Silver...

2. combined state:- The metals which are most reactive are found in the combined state. Eg:- Mercury, Copper...

Question-23. What are minerals and ores called?

Ans-

minerals– The naturally occurring elements or compounds in the earth's crust are called minerals.

ore– The minerals from which metals can be obtained easily and at low cost are called ores.

Question-24. What is the difference between mineral and ore?

Ans- Following is the difference between mineral and ore—

Question-25. Who is Metallurgist? Write its various stages?

Ans- The process of obtaining pure metal from ore is called metallurgy.

Its various stages are as follows—

• Ore concentration.

• Conversion of concentrated ore into metal oxide.

• Extraction of metals from metal oxides.

• Metal purification.

Question-26. What is a gang (matrix) or adhatri called?

Ans- The impurities present in the minerals like clay, sand, stone pieces etc. are called matrix and the impurities present with the ores are called gangue.

Question-27. What are the methods of enrichment (concentration) of ores?

Ans- Following are the methods of enrichment of ores—

• hand picking

• Gravity Separation Method

• froth-flotation method

• Electromagnetic Separation Method

• chemical separation method.

Question-28. Into how many classes are metals classified on the basis of reactivity?

Ans- On the basis of reactivity, metals are divided into three classes.—

• low reactive metals– Platinum, Gold, Silver, Mercury (Mercury), Copper

• intermediate reactive metals– Magnesium, Aluminum, Zinc, Iron, Tin, Lead

• highly reactive metals– lithium, potassium, sodium, calcium

Question-29. What is called Bharjan (Jaran) and Nistapan?

Ans-

Bharjan (Jaran)– On heating the sulphide ore in the presence of air at high temperature, it turns into oxide and volatile impurities are released. This process is called Bharjan (Jaran).

2ZnS + 3O₂ → 2ZnO + 2SO₂

disposal- On heating the carbonate ore in the presence of confined air at high temperature, it turns into oxide and volatile impurities are released. This process is called quenching.

ZnCo₃ → ZnO + Co₂

Question-31. What is rusting?

Ans- When iron is left exposed for a long time in the air, due to exposure to light and moisture, gradually a brown layer is deposited on it, which is called rusting.

There is a way to prevent rust—

• By painting iron metals.

• Grease or oil.

Question-32. What is Corrosion?

Ans- Corrosion is the chemical process in which reactive metals react with moist air to form undesirable substances. In this process, the metal reacts with the moisture present in the atmosphere and oxygen or other gases to form oxides, hydroxides, carbonates or sulfides of the metal, due to which the layer of the metal peels off, which causes corrosion.

Question-33. What are the conditions of corrosion, and what are the measures to reduce it?

Ans-

conditions for corrosion—

• presence of air (oxygen)

• presence of moisture

• presence of reactive metal

Ways to reduce corrosion—

• by painting metals

• oil and grease

• by succession and anodization

Question-34. What are Yashdalepan (galvanization), alloy and amalgam called?

Ans-

Galvanization:- The process of coating iron with a thin layer of zinc metal to prevent rusting is called galvanization.

Alloy:- A mixture of two or more metals or a metal and a non-metal is called an alloy.

Amalgam:- When an alloy contains mercury, it is called amalgam. Eg:- sodium amalgam, tin amalgam etc.

Question-35. What happens when zinc is added to a solution of iron sulphate? Write its chemical reaction.

Ans- When zinc is added to a solution of iron sulphate, zinc displaces iron from the solution of iron sulphate.

Zn + FeSO₄ → ZnSo₄ + Fe

Question-36. Why do ionic compounds have high melting points?

Ans- Ionic compounds are made up of ions with positive and negative charges and these ions are very strongly bound to each other by the force of electric attraction. More energy is needed to reduce this force of attraction. Hence the ionic compound has a high melting point.

Question-37. Name two metals which will displace hydrogen from a dilute acid and two metals which cannot do so.

Ans-

metal that displaces hydrogen from dilute acid– Magnesium (Mg), Zinc (Zn)

metal that does not displace hydrogen from a dilute acid– Copper (Cu), Gold (Au)

Question-38. What will form the anode, cathode and electrolyte in the electrolytic refining of a metal M?

Ans- A thick piece of impure M metal is made the anode, and a thin strip of pure M metal is made the cathode. Water soluble M metal salts are used for electrolysis.

Question-39. What kind of oxide do nonmetals form when combined with oxygen?

Ans- Non-metals combine with oxygen to form acidic or neutral oxides.

• C + O₂ → CO₂ (acidic oxide)

• 2C + O₂ → 2CO (neutral oxide)

Question-40. Why are platinum, gold and silver used to make jewellery?

Ans- Platinum, gold and silver are very rarely reactive metals, due to which they do not corrosion, and their luster is also maintained. Hence they are used for making jewellery.

Question-41. Aluminum is a very reactive metal. Still it is used to make cooking utensils, why?

Ans- Aluminum is a good conductor of heat. Its corrosion is also very less. Therefore, aluminum is used in cooking utensils despite being a highly reactive metal.

Question-42. Carbonate and sulphide ores are converted into oxides in the extraction process, why?

Ans- Metal is easier to extract from oxide ores than from sulfides or carbonates. Therefore, the carbonate and sulfide ores are converted into oxides in the extraction process.

Question-43. You must have seen dirty copper utensils cleaned with lemon or tamarind juice. Why are these sour substances effective in cleaning utensils?

Ans- Due to the deposition of green layer of alkaline copper carbonate on copper, its color becomes discolored. When these utensils are cleaned with lemon or tamarind juice, the acidic substance present in lemon or tamarind reacts with alkaline copper carbonate and separates it from the copper vessel, due to which the vessel becomes clean and shines.

Question-44. You are given a hammer, battery, bulb, wire and switch.

(a) How can you differentiate between samples of metals and non-metals using this?

Ans:- First of all we will decorate all the equipment and make a circuit. After that we will turn on the switch installed in the circuit. If the bulb lights up, then the given sample is metal.

(b) Assess the usefulness of these tests for distinguishing between metals and non-metals.

Ans:- This test is very useful for distinguishing between metals and non-metals. In this only graphite is an exception, because graphite is a good conductor of electricity even though it is a non-metal.

Question-45. Neelu took the sulfur powder in a spatula and heated it. He collected the gas emitted.

(a) What will be the action of the gas?

1. on dry litmus paper:- There is no action on dried litmus paper.

2. on wet litmus paper:- The gas turns moist blue litmus paper red.

(b) Write balanced chemical equations for the above reactions.

Ans:- S + O₂ → SO₂

Question-46. A person goes to every house as a goldsmith. He pretended to make old and dirty gold ornaments shine as before. Without a doubt, a woman gives him her gold bracelets, which he dips into a special solution. The bracelets shine like new, but their weight is greatly reduced. The woman is very sad, and after an argument, the man has to bow down. Like a detective can you tell about the nature of that solution?

Ans- Yes, that solution is aquaregia, which is a fresh mixture of concentrated HCl acid and concentrated HNO₃ acid in the ratio of 3:1, which has the ability to melt gold.

Question-47. Metallic oxides of zinc, magnesium and copper were heated with the following metals. Under what conditions will the displacement reaction take place.

Ans- We know that a more reactive metal displaces a metal from an oxide of a less reactive metal. Therefore, of the three metals, magnesium will be the most reactive metal. Then there will be zinc and copper.

Question-48. Show the formation of Na₂O and MgO by transfer of electrons.

Ans- will be published soon

Question-49. Give examples of how many states of non-metals exist.

Ans- There are three states of non-metals—

• Solid:- Carbon, Sulfur, Phosphorus, Iodine

• liquid:- bromine

• gas:- Hydrogen, Oxygen, Nitrogen, Chlorine, Helium, Argon

Question-50. Write the reaction of non-metals with water and with acid?

Ans-

reaction with water:- Non-metals do not react with water. If a non-metal reacts with water, it does not form hydrogen gas.

reaction with acid:- Non-metals do not displace hydrogen when they react with acids, because non-metals can take electrons from other atoms but cannot give electrons to others.

Question-51. Write the equation for the following reaction.

(a). iron with steam

⇒ 2Al + 3H₂O (steam) → Al₂O₃ + 3H₂

(b). calcium with water

⇒ Ca + 2H₂O (cold water) → Ca(OH)₂ + H₂

(c). potassium with water

⇒ 2K + 2H₂O (cold water) → 2KOH + H₂

(d). sodium with water

⇒ 2Na + 2H₂O (cold water) → 2NaOH + H₂ + thermal energy

(e). copper with oxygen

⇒ 2Cu + O₂ + 2CuO

(f). aluminum with oxygen

⇒ 4Al + 3O₂ → 2Al₂O₃

(g). H₂SO₄ with iron

⇒ Fe + H₂SO₄ → FeSO₄ + H₂

(h). HCl with aluminum oxide

⇒ Al₂O₃ + 6HCl → 2AlCl₃ + 3H₂O

Question-52. Write the atomic numbers of the following elements.

Ans-

Question-53. How many types of ores are there?

Ans- There are mainly four types of ores—

• oxide ore

• sulfide ore

• carbonate ore

• halide ore

Question-54. What is the average of the atomic masses of lithium and potassium?

Ans-

Atomic mass of lithium (Li) = 7

Atomic mass of potassium (K) = 39

Question-55. Mention the uses of the following alloying components.

(a) steel (b) brass (c) bronze (d) ispat

(a) Steel (Stainless Steel):- Iron → 73%, Nickel → 8%, → 18%, → 1%

• Use:- In the manufacture of motor and bicycle parts, utensils, knives, blades, etc.

(b) brass:- Copper → 80%, Zinc → 20%

• Use:- In making utensils, idols, coins, locks, cartridges etc.

(c) bronze:- Copper → 88%, Tin → 12%

• Use:- In making utensils, idols, coins etc.

(d) ispat:- Iron → 98.5%, Carbon → 1.5%

• Use:- In bridges, ships, buildings, railway lines, etc.

Question-56. What do you understand by catalyst?

Ans- Catalysts are substances that increase or decrease the rate of a reaction but they themselves remain unchanged at the end of the reaction because they do not take part in the reaction.

Question-57. What is the difference between Washing Soda and Baking Soda?

Ans- What is the difference between Washing Soda and Baking Soda?—

Question-58. Why is distilled water not a conductor of electricity while rain water is?

Ans- The salt content in distilled water is very less, whereas the amount of salt in rain water is very high. Therefore, due to high salt content, rain water is a conductor of electricity and distilled water is not a conductor of electricity.

Question-59. What is connectivity? and write the valency of magnesium.

Ans- The number of electrons present in the outermost shell of an atom of an element is called the valency of that element.

Atomic number of magnesium = 12

Electronic configuration = 2, 8, 2

Its valency = 2

Question-60. Why does a metal not release hydrogen gas when it reacts with nitric acid?

Ans- will be published soon

Question-61. Who is Anode Punk?

Ans- will be published soon