Best NCERT Solutions for Class 10 Science Chapter 3 Metals and Non metals

NCERT Solutions for Class 10 Science Chapter 3 Metals and Non-metals

Best NCERT Solutions for Class 10 Science Chapter 3 Metals and Non metals .Elements are divided into two main groups in the field of chemistry: metals and non-metals. Their unique characteristics, behaviours, and uses are examined in this chapter, which clarifies their importance in both nature and technology.

Intext Questions:

1. Give an example of a metal which

i. is a liquid at room temperature.

Answer: Mercury

ii. can be easily cut with a knife.

Answer: Potassium

iii. is the best conductor of heat.

Answer: Copper and Silver

iv. is a poor conductor of heat.

Answer: Mercury.

2. Explain the meanings of malleable and ductile.

Answer: Malleable: Malleability is the quality of a metal that allows it to be pounded into thin sheets; the metal is said to possess this property.

Ductile: A metal is said to be ductile if it possesses the property that allows it to be pounded into thin pipes or wire.

Intext Questions:

1. Why sodium is kept immersed in kerosene oil?

Answer: The element sodium is extremely reactive. As soon as it comes into touch with air, it reacts with it and starts to burn. Therefore, sodium is always submerged in kerosene oil to prevent such mishaps.

2. Write equations for the reactions of

i. iron with steam

Answer: $3 F e (s) + 4 H 2 O (g) \to F e 3 O 4 (s) + 4 H 2 (g)$

ii. calcium and potassium with water

Answer: $C a (s) + 2 H_{2} O (l) \to C a (O H)_{2} (a q) + H_{2} (g)$

$2 K (s) + 2 H_{2} O (l) \to 2 K O H (a q) + H_{2} (g) +$ heat

3. 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:

Metals	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
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.

According to the activity series the most reactive metal displaces the least reactive metal. according to the given table we can say that:

$A$ is less reactive than iron but more reactive with copper.

$A + {F e S O}_{4} \to No reaction$

$A + {C u S O}_{4} \to Single Displacement$

B is more reactive than iron but less reactive than zinc.

$B + {F e S O}_{4} \to Single Displacement$

$B + {Z n S O}_{4} \to No reaction$

$C$ is less reactive than iron, copper and zinc but more reactive with silver

$C + {F e S O}_{4} \to No reaction$

$C + {C u S O}_{4} \to No reaction$

$C + {Z n S O}_{4} \to No reaction$

$C + {A g N O}_{3} \to Single Displacement$

D is less reactive than iron, copper,zinc, and silver

$D + {F e S O}_{4} \to No reaction$

$D + {C u S O}_{4} \to No reaction$

$D + {Z n S O}_{4} \to No reaction$

$D + {A g N O}_{3} \to No Reaction$

Which is the most reactive metal?

Answer: B is the most reactive metal.

$B + FeS O_{4} \to Single Displacement$

2. What would you observe if B is added to a solution of copper (II) sulphate?

Answer: When B is added to a solution of copper (II) sulphate then it shows the single displacement because B is more reactive than iron.

$B + CuS O_{4} \to Single Displacement$

iii. Arrange the metals A, B, C and D in the order of decreasing reactivity.

Answer: $B > A > C > D$

Which gas is produced when dilute hydrochloric acid is added to a reactive metal? Write the chemical reaction when iron reacts with dilute $H_{2} {S O}_{4}$ .

Answer: The reactivity series indicates that iron is more reactive than hydrogen. Thus, iron replaces hydrogen to produce iron sulphate when it comes into touch with diluted H2SO4, releasing hydrogen gas in the process.

Fe(s)+H2SO4(aq)→FeSO4(aq)+H2(g)

5. What would you observe when zinc is added to a solution of iron (II) sulphate? Write the chemical reaction that takes place.

Answer: Zinc is known to be more reactive than iron based on the reactivity series. Zinc therefore creates zinc sulphate when it comes into touch with iron sulphate solution, replacing iron. Additionally, solutions change from green to brown in hue.

Zn(s)+FeSO4(aq)→ZnSO4(aq)+Fe(s)

Best NCERT Solutions for Class 10 Science Chapter 3 Metals and Non metals

Intext Exercise:

1. Answer the following:

i. Write the electron-dot structures for sodium, oxygen and magnesium.

Answer: The atomic numbers of magnesium, oxygen, and sodium are 11, 8, and 12. Below are the electron dot structures:

Sodium (2,8,1) = $\overset{X}{Na}$

Oxygen (2,6) =

Magnesium (2,8,2) = $\overset{XX}{Mg}$

ii. Show the formation of $N a_{2} O$ and MgO by the transfer of electrons.

Answer: An ionic link will form between the two chemicals.

iii. What are the ions present in these compounds?

Answer: In the ${N a}_{2} O, the ions 2 {N a}^{+} and O^{2} - and in M g O are {M g}^{2 +} and O^{2} -$ .

2. Why do ionic compounds have high melting points?

Answer: Ionic compounds are stiff and firmly packed because of the strong electrostatic force between the molecules. The high melting points of ionic compounds are the result of this tight packing.

Refer to page 53.

1. Define the following terms.

i. Minerals:

Answer: Ores are composed of a mixture of extractable impurities and metallic compounds, while a mineral is a naturally occurring compound of a metal.

ii. Ore:

Answer: Ores are the minerals from which metals can be economically and conveniently mined.

iii. Gangue:

Answer: There are certain impurities in the ore, such as sand, clay, and rough stuff. These contaminants are referred to as matrix or gangue. Prior to the metallurgical process commencing, the gangue is eliminated.

2. Name two metals which are found in nature in the free state.

Answer: Since they have relatively little potential for reactivity, gold and silver are found in their free state.

For instance, platinum (Pt), gold (Au), and silver (Ag).

3. What chemical process is used for obtaining a metal from its oxide?

Answer :

The electrolysis procedure reduces more reactive metals. Carbon or carbon monoxide can both decrease moderate reactive metals. Metal oxides can be reduced by highly reactive metals removing the metals from their oxides or by utilising appropriate reducing agents, like carbon. For instance, heating zinc oxide with carbon reduces it to metallic zinc.

${Z n O}_{(s)} + C_{(s)} \overset{Δ}{⟶} {Z n}_{(s)} + {C O}_{(g)}$ or

$Z n O + C O \to Z n + {C O}_{2}$

Thermite process: By treating chromium oxides with aluminium powder, chromium oxides are converted to chromium. In this instance, manganese is displaced from its oxide by aluminium.

$C r_{2} O_{3} + 2 Al \to A l_{2} O_{3} + 2 Cr + heat$

Refer to page 55.

1. Metallic oxides of zinc, magnesium and copper were heated with the following metals.

Metals	Zinc	Magnesium	Copper
Zinc Oxide	–	–	–
Magnesium Oxide	–	–	–
Copper Oxide	–	–	–

In which cases will you find displacement reactions taking place?

Answer:

Metals	Zinc	Magnesium	Copper
Zinc Oxide	No reaction	Displacement	No reaction
Magnesium Oxide	No reaction	No reaction	No reaction
Copper Oxide	Displacement	Displacement	No reaction

2. Which metals do not corrode easily?

Answer: less reactive metals, like gold, silver, and platinum.

3. What are alloys?

Answer: A homogenous combination of two metals or of metal and non-metals is called an alloy. Melting the metals, combining them, and then hardening them into alloys is how they are created.

Example: An alloy of copper and tin is called bronze.

Exercise Questions

1. Which of the following pairs will give displacement reactions?

(a) $N a C l$ solution and copper metal

(b) $M g C l_{2}$ solution and aluminium metal

(c) $F e S O_{4}$ solution and silver metal

(d) $A g N O_{3}$ solution and copper metal.

Answer: (d) $A g N O_{3}$ solution and copper

2. 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 of the above.

Answer: (c) Applying a coating of zinc

3. 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

Answer: (a) calcium

4. 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 more reactive than tin.

(d) zinc is less reactive than tin.

Answer: (c) zinc is more reactive than tin.

5. You are given a hammer, battery, bulb, wires and a switch.

(a) How could you use them to distinguish between samples of metals and non-metals?

Answer: Metals are pliable by nature. With the use of a hammer, we can defeat the provided sample. It is metal if it becomes thin sheets; if not, it is nonmetal.

Electricity is carried by metals. when we build a circuit using a battery, cables, a lamp, and a switch. If the lightbulb illuminates, released electrons in the sample have made it metallic. The sample is non-metallic if the lightbulb does not illuminate.

(b) Assess the usefulness of these tests in distinguishing between metals and nonmetals.

Answer: These tests illustrate the physical characteristics of metals and non-metals. Because of their physical differences, we can tell them apart with ease.

6. What are amphoteric oxides? Give two examples of amphoteric oxides.

Answer: Amphoteric oxides are oxides that exhibit a bifurcation behaviour towards both bases and acids.

Example: Aluminium oxide (Al2O3) and zinc oxide (ZnO)

7. Name two metals which will displace hydrogen from dilute acids, and two metals which will not.

Answer: Hydrogen from its diluted acids will be replaced by more reactive metals. for instance, zinc and iron.

$F e + 2 H C l \to {F e C l}_{2} + H_{2}$

$Z n + 2 H C l \to {Z n C l}_{2} + H_{2}$

Hydrogen in its diluted acids will not be replaced by least reactive metals. for instance, silver and copper

$C u + H C l \to$ No Reaction

$A g + H C l \to$ No Reaction

8. In the electrolytic refining of a metal M, what would you take as the anode, the cathode and the electrolyte?

Answer:

When a metal M is refined electrolytically:

i. Cathode → Metal pure M

ii. Pure metal M at the anode

ii. Electrolyte → Metal M Salt Solution

9. 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 figure below.

(a) What will be the action of gas on

i. dry litmus paper?

Answer: dried litmus paper yields no response.

ii. moist litmus paper?

Answer: Sulphur dioxide will develop and cause moist blue litmus to become red. When sulphur dioxide reacts with water, it becomes sulphurous acid, which is acidic oxide.

(b) Write a balanced chemical equation for the reaction taking place.

Answer: $S_{(s)} + O_{2 (g)} ⟶ {S O}_{2 (g)}$

${S O}_{2 (g)} + H_{2} O_{(l)} ⟶ \underset{Sulphur dioxide}{⟶} H_{2} {S O}_{3 (a q)}$

10. State two ways to prevent the rusting of iron.

Answer: Rusting is the process by which metals deteriorate in the presence of air and water. Rusting can be avoided in the following two ways:

Painting: It keeps iron from getting into contact with water or the air directly.

Galvanization: Zinc is applied to iron by this technique.

11. What type of oxides is formed when nonmetals combine with oxygen?

Answer: Acidic oxides are created when non-metals react with oxygen; these oxides then react with water to form acidic solutions.

12. Give reasons

(a) Platinum, gold and silver are used to make jewelers.

Answer: These metals are ideal for jewelry-making because they are glossy and extremely low reactive.

(b) Sodium, potassium and lithium are stored under oil.

Answer: Because they are extremely reactive metals, they ignite the moment they come into touch with air. Therefore, these metals are constantly submerged in oil to prevent any mishaps.

(c) Aluminium is a highly reactive metal, yet it is used to make utensils for cooking.

Answer: Because aluminium is extremely reactive, it reacts with atmospheric oxygen to generate the stable molecule Al2O3. They also transfer heat quite well in addition to this. As a result, cooking utensils are made of aluminium.

(d) Carbonate and sulphide ores are usually converted into oxides during the process of extraction.

Answer: Metals are easier to extract from their oxides than from their carbonate and sulphide forms. Thus, roasting and calcination are the usual processes used to turn ores into oxides.

13. 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.

Answer: When copper reacts with atmospheric damp carbon dioxide, it generates basic copper carbonate (CuCO3.Cu(OH)2). The copper vase loses its glossy brown sheen and turns green. The layer dissolves when the basic copper carbonate is neutralised by the citric acid found in lemons and tamarinds.

14. Differentiate between metals and non-metals.

Answer: The following are the ways that metals and non-metals differ:

METALS	NON-METALS
Metals are electropositive.	Non-metals are electronegative.
They react with water to form oxides and hydroxides. Some metals react with cold water, some with hot water, and some with steam. $2 Na + 2 H_{2} O \to 2 NaOH + H_{2} ↑$	They do not react with water.
They react with oxygen to form basic oxides $4 Na + O_{2} \to 2 N a_{2} O$ ese have ionic bonds.	They react with oxygen to form acidic or neutral oxides. $C + O_{2} \to C O_{2}$ These have covalent bonds
They react with dilute acids to form a salt and evolve hydrogen gas. However, Cu, Ag, Au, Pt, Hg do not react. $2 Na + 2 HCl \to 2 NaCl + H_{2} ↑$ .	They do not react with dilute acids. These are not capable of replacing hydrogen.
They react with the salt solution of metals. Depending on their reactivity, displacement reaction can occur $CuS O_{4} + Zn \to ZnS O_{4} + Cu$ .	These react with the salt solution of non-metals
They act as reducing agents. $Na \to N a^{+} + e^{-}$	These act as oxidizing agents. $C l_{2} + 2 e^{-} \to 2 C l^{-}$

15. 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?

Answer: The man is using Aqua Regia, a solution made up of one part HNO3 and three parts HCL. Even though gold is the least reactive metal, when it is submerged in aqua regia, the outermost layer dissolves and the inner layer emerges, making the gold appear lighter but more lustrous.