NCERT Solutions Class 7 Science Chapter 4 - The World of Metals and Non-Metals

Metals and nonmetals are the building blocks of the modern world. Iron and steel are the foundation of tall skyscrapers; oxygen is vital for life; carbon is in our pencils. NCERT Solutions Chapter 4 of the Class 7 Science class acts as the bridge to the existing knowledge on the properties, behaviour, and uses of metals and nonmetals; it introduces students to core chemistry ideas.

For example, it explained that metals are usually hard, shiny, and good conductors, while nonmetals are likely dull, brittle, and insulators. It also described how metals and nonmetals react with air, water, acids, and bases, and enabled students to see and experiment and learn chemistry rather than simply read or listen.

1.0NCERT Solutions Class 7 Science Chapter 4 - The World of Metals and Non-metals – Download PDF

Download the free PDF of NCERT Solutions for Class 7 Science Chapter 4 from below:

2.0Key Concepts in Chapter 4 – The World of metals and non-metals

Chapter Overview: Metals and Nonmetals 

Metals and nonmetals can be categorized based on their physical and chemical properties. This chapter discusses:

• What is metal and nonmetal?  
• How can they be distinguished based on appearance, hardness, malleability and conductivity? 
• How do they react with air, water and acids? 
• How do we use them in everyday life?

These concepts are discussed with examples and simple experiments to foster an understanding of these concepts, while also helping students to visualize and make connections with the theory and the world outside.

Physical properties of metals and nonmetals 

• Metals are usually shiny (lustrous), hardness, malleable (can be made into sheets), ductile (can be made into wire), sonorous (ringing sound), good conductors of heat and electricity.
• Nonmetals usually dull, brittle and poor conductors (with graphite being a notable exception) 

Chemical properties 

• Reaction with oxygen: metals form basic oxides, nonmetals form acidic oxides. 
• Reaction with water - some metals (sodium) react vigorously with water. 
• Reaction with acids - metals usually form hydrogen gas when they react with acids! 
• Nonmetals usually do not undergo a reaction with dilute acids! 

Displacement reactions 

• More reactive metals can displace less reactive metals from the compounds.- this is an important consideration when assessing reactivity.

Applications in Everyday Life

• Metals such as iron, aluminum, and copper are utilized in building, transportation, and electrical wire.
• Non-metals, such as oxygen, nitrogen, sulfur, and chlorine, are found in breathing, pesticides, antiseptics, and so forth.

Important Science and Applications

At Home

• Colloquially, metals are used as the utensils we eat with, tools we work with, wires we conduct electricity with, and coins we use to pay for things, due to their strength and conductivity.
• Medications like iodine, phosphorus, or chlorine, and products like hand sanitizers or bleach are often made from non-metals.

In Nature

• Oxygen is required for respiration.
• Nitrogen is a critical component in agriculture (fertilizers).
• Carbon is a basic element of all living organisms and fuels.

In Industry

• Metals are used extensively in manufacturing or in building structure and appliances.
• Non-metals support the processes used to manufacture plastics, explosives, or water-purifying chemicals.

Promoting Scientific Inquiry

This chapter promotes curiosity through asking students to explore the ‘how and why’ material behaves in everyday settings:

• Why do metal wires conduct electricity but rubber does not?
• Why does iron rust when it is left in the rain?
• Why are copper and aluminum used in wires?
• Why should we not use wood or plastic in electrical appliances?

Simple demonstrations in class often lead students to reasonable conclusions based on their observables in everyday settings.

3.0NCERT Class 7 Science Chapter 4 The World of Metals and Non-Metals: Detailed Solutions

• Which metal is commonly used to make food packaging materials as it is cheaper, and its thin sheets can be folded easily into any shape? (i) Aluminium (ii) Copper (iii) Iron (iv) Gold Ans. Option (i) Aluminium metal is used to make food packaging materials as it is cheaper, and its thin sheets can be folded easily into any shape.
• Which of the following metal catches fire when it comes in contact with water? (i) Copper (ii) Aluminium (iii) Zinc (iv) Sodium Ans. (iv) Sodium is high reactive metal, it catches fire when it comes in contact with water.
• State with reason(s) whether the following statements are True [T] or False $[\mathrm{F}]$. (i) Aluminium and copper are examples of non-metals used for making utensils and statues. [F] Ans. (i) Aluminium and copper are metals used for making utensils and statues. (ii) Metals form oxides when combined with oxygen, the solution of which turns blue litmus paper to red. [F] Ans. (ii) Metals form oxides when combined with oxygen, the solution of which turns red litmus paper to blue. (iii) Oxygen is a non-metal essential for respiration. [T] Ans.(iii) Oxygen is a non-metal essential for respiration. (iv) Copper vessels are used for boiling water because they are good conductors of electricity. [F] Ans. (iv) Copper vessels are used for boiling water because they are good conductors of heat.
• Why are only a few metals suitable for making jewellery? Ans. Only a few metals Gold, silver and platinum are suitable for making jewellery because they do not lose shine easily most malleable and ductile and have mature lustre on the surface.
• Match the uses of metals and non-metals given in Column I with the jumbled names of metals and non-metals given in Column II.

(i) - (c) Copper (ii) -(e) Gold (iii) -(a) Oxygen (iv) -(d) Nitrogen (v)-(b) Chlorine

• What happens when oxygen reacts with magnesium and sulfur. What are the main differences in the nature of products formed? Ans. Magnesium ribbon burns with a dazzling white flame and changes into a white powder. This powder is magnesium oxide. It is formed due to the reaction between magnesium and oxygen present in the air. On adding a few drops of warm water to this white powder and stirring, it is observed that it changes the colour of red litmus paper to blue hence, it is basic in nature. On burning sulfur in air (oxygen), sulfur dioxide gas is formed. It is acidic in nature. On dissolving sulfur dioxide gas in water, sulfurous acid is formed.
• Complete the following flow chart:
  
  Ans. Magnesium, Magnesium hydroxide, No change.
• You are provided with the following materials. Discuss which material would be your choice to make a pan that is most suitable for boiling water and why? Iron, copper, sulfur, coal, plastic, wood, cardboard Ans. Among the given materials, only iron and copper are metals, and both are good conductors of heat. However, copper is the best choice because it is highly resistant to rust compared to iron. Therefore, a pan made of copper is the most suitable choice for boiling water.
• You are provided with three iron nails, each dipped in oil, water and vinegar. Which iron nail will not rust, and why? Ans. The iron nail dipped in oil will not rust because the oil prevents the iron nail from coming into contact with air or moisture. It forms a protective layer on the metal, which prevents rusting.
• How do the different properties of metals and non-metals determine their uses in everyday life? Metals and non-metals have various properties that make them useful in our everyday life. Ans. Metals:

• Metals are malleable, for example, aluminium foil is used for wrapping food.
• Metals are ductile, wires made of copper or aluminium are used in electrical fittings.
• Metals are sonorous, they produce a ringing sound.
• Metals are good conductors of heat, so they are used in making cooking vessels.
• Metals are good conductors of electricity, making them ideal for electrical wires. Non-metals:
• Generally non-metals are poor conductor of heat and electricity; for example, sulphur and carbon are used in insulating materials to prevent the transfer of heat or electricity.
• Non-metals are brittle: for example, sulphur and phosphorus are often used in matchsticks as they break easily or react quickly.
• Non-metals are gaseous at room temperature: for example, oxygen is essential for breathing.
• Non-metals are non-lustrous: carbon (as graphite) are used in pencils and dry cell batteries.

• One of the methods of protecting iron from getting rusted is to put a thin coating of zinc metal over it. Since sulfur does not react with water, can it be used for this purpose? Justify your answer. Ans. No, sulphur cannot be used to protect iron from rusting. While sulphur does not react with water, it does not have the property of forming a protective layer over iron like zinc. It cannot prevent air and moisture from coming into contact with the iron.
• An ironsmith heats iron before making tools. Why is heating necessary in this process? Ans. For making tools, a ironsmith first heats a piece of iron until it becomes red-hot. This is because heating makes the iron soft, more malleable and easier to bend, hammer and mould into the desired shape for tool.

4.0Key Features of NCERT Solutions – Chapter 4 : The World of Metals and Non-metals

1. Clarity of Concept: The author's explanations highlight differences between metals and non-metals using examples, activities, and simple language in the use of scientific terms. Likewise, students are learning not only "what," but also "why." 
2. Thorough Gradual Responses: All in-text book questions and end-of-chapter exercises are also solved with an explanation that helps students feel confident in their understanding of the material specifically for assessment in the chapter as well as in future learning. 
3. Support of Scientific Thinking: The solutions outline the importance of experimentation and logic, which is essential for developing the skills in future scientists. 
4. Real-World Connections: Examples and practical uses provide student input for relating textbook materials to their world, increasing the interest of students and taking from the text. 
5. Improved Retention: Using tables, comparisons, and real world connections help to improve retention and understanding of the topic.