Important Questions Class 8 Science Chapter 4

Important Questions Class 8 Science Chapter 4 – Materials: Metals and Nonmetals

Class 8 Science Chapter 4 is about different metals and nonmetals found on Earth. Everything surrounding us is categorised into either metals or nonmetals. Hence, it is very crucial to know what nonmetals and metals are and how to distinguish between them. Chapter 4 Class 8 Science important questions discuss metals’ and nonmetals’ various physical and chemical properties. To help you with this, we list a few physical and chemical properties of metals and nonmetals.

Important questions in Class 8 Science Chapter 4 will give you a vivid description of metals and nonmetals in this chapter. These solutions will help broadly during the exams and also for their preparation. These chapter-wise solutions contain essential question answers and some solved questions that may come in the examination. These solved questions of the Important questions Class 8 Science Chapter 4 will make revision easier for students before the exams. Class 8 Science Chapter 4 important questions are easy and scored. During the exams, if you follow the sample questions provided, it will clear all doubts. The solutions will help understand the metals and nonmetals of the Class 8 important questions, both critically and logically.

To help students score good grades and prepare for their examinations, they must clearly understand the topics and practice solving many questions. For this purpose, the expert panel at Extramarks has curated various studies and practice materials such as NCERT Solutions, CBSE Revision notes, NCERT books, and CBSE sample papers. 

A comprehensive list of important questions Class 8 Science Chapter 4 is compiled carefully per the CBSE syllabus and NCERT guidelines, helping the student understand the exam question pattern. To get maximum benefit, students are advised to practise these questions honestly through Science Class 8 Chapter 4 important questions on the Extramarks website.

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Important Questions Class 8 Science Chapter 4 – With Solutions

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The below-given list consists of a few questions along with answers from our question bank of Important Questions Class 8 Science Chapter 4:

Question 1. Which of the following can be beaten into thin sheets?

• Zinc
• Phosphorous
• Sulphur
• Oxygen

Answer 1: The correct option is A.

Explanation:

Elements are mainly classified into metals and nonmetals. Out of all these, metals can be drawn into thin sheets, and the property by which metals can be beaten to thin sheets without cracking is known as malleability. Zinc is a mineral essential for human health but in very trace quantities. Zinc is also used to make alloys such as brass, nickel, and silver and the manufacture of paints, textiles, and other electrical equipment, and employment in pharmaceuticals. Zinc has good malleability, whereas the rest of the options are nonmetals, which do not display the unique property of being beaten into thin sheets. Zinc is a metal which shows malleability and ductility, whereas phosphorus, sulphur and oxygen are nonmetals which lack malleability and ductility.

Question 2. Give reasons for the following: sodium and potassium are stored in kerosene.

Answer 2: 

Sodium and potassium metals have very high reactivity. When kept open, they come in contact with the atmosphere and undergo a spontaneous reaction. Sodium and potassium are highly reactive. Due to this vigorous reaction, sodium and potassium quickly catch fire due to exposure to water vapour present in the air. You can prevent this if you store sodium and potassium in kerosene. Sodium and potassium are covered with kerosene, so they cannot come in contact with air. This prevents accidental fires.

Question 3. State the chemical properties of metal.

Answer 3: 

Metal oxides generally form when metals react with oxygen to generate basic metal oxides. When dipped in a rust solution (essentially a metal, iron), a red litmus paper turns blue, suggesting the formation of a primary metal oxide. Some metals react very quickly with water, such as sodium, which is why it is usually preserved in kerosene, whereas other metals, such as iron, react comparatively slowly. Metals react with water for the generation of metal hydroxides and hydrogen gas. Metal salts and hydrogen gas are formed when these metals react with acids. When a burning matchstick is placed in the opening of a test tube containing a magnesium ribbon and weak hydrochloric acid, we can hear a pop sound. This sound is produced owing to the combustion of hydrogen gas during the reaction.

Metal salts and hydrogen gas are formed when metals such as aluminium and zinc combine with the bases such as sodium hydroxide to give metal salts and hydrogen gas, which burns with a pop sound. Metals in the aqueous solutions tend to displace more reactive metals from less reactive metals in their compounds. We can observe that the blue colour of copper sulphate and the aqueous zinc solution fades, and a red deposit forms at the bottom. This is because zinc is considered more reactive than copper, which replaces it and creates zinc sulphate, releasing red copper.

Question 4. List some uses of nonmetals.

Answer 4: 

A nonmetal in chemistry can be defined as a chemical element that generally gains electrons when reacting with a metal in a chemical reaction. It tends to form an acid if combined with oxygen and hydrogen. The nonmetals display more variety in colour and state in comparison to metals. Substances which are soft and dull, i.e., non-lustrous, non-sonorous, non-ductile, non-malleable and poor conductors of heat and electricity, are called nonmetals—for example, oxygen, hydrogen, sulphur, etc.

• Chlorine is used in the making of bleaching powder and liquid bleach, which are used for cleaning purposes.
• Chlorine is also a very efficient disinfectant, hence added in public water to kill disease-causing pathogens.
• Noble gases like neon, argon, and krypton are used in different types of lights.
• Diamond is often used in industries for cutting glass, etc.
• Coal, a form of carbon, is used as a fuel.
• Nitrogen is utilised in the manufacturing of ammonia.
• Oxygen cylinders are used for breathing in emergency cases.
• Iodine is used as tincture iodine 

Question 5. State the physical properties of metals and nonmetals

Answer 5:

• Metal

Metal in the subject of chemistry is defined as an element that can easily form positive ions known as cations and tends to form metallic bonds. These metals are distinguished by their chemical and physical properties, such as malleability, ductility, ionisation and bonding properties.

• Physical Properties of Metals

Some of the major physical properties of metals are given below:

Metals can be shaped into thin sheets due to the features they possess. This feature is termed malleability. This enables the material to change shape and form thin sheets, such as silver or aluminium foil. Metals also have a characteristic called ductility that allows them to be pulled into wires. Because of this feature, metals such as copper to be pulled into wires. Metals are also excellent heat conductors which are used to make cooking utensils, irons, and heaters, among other things. Metals like copper and aluminium make cables and electric lines because they are good conductors of energy. When these metals are hammered firmly, they have the unique feature of producing a distinct ringing sound. This is referred to as resonance. When a metal surface is struck, you hear a sound because of this very feature. Gold and silver, additionally, have a brilliant aspect.

• Nonmetal

A nonmetal in chemistry can be defined as a chemical element that generally gains electrons when reacting with a metal in a chemical reaction. It tends to form an acid if combined with oxygen and hydrogen. The nonmetals display more variety in colour and state in comparison to metals. 

•  Physical properties of nonmetals 

Some of the major physical properties of nonmetals are given below:

When nonmetals are brittle and also disintegrate into powder when hammered, they are non-malleable. Sulphur, as an example, develops into a powdery substance. Except for carbon, nonmetals are not ductile because they cannot be pulled into wires. Carbon fibres are commonly employed in sports and musical instruments. Besides graphite, the only nonmetal that conducts heat and electricity, nonmetals are poor conductors of heat and electricity. The nonmetals are not sonorous, making no sound when hit. When a wooden box is struck, it cannot generate a ringing sound. Nonmetals are non-lustrous, which means they have a soft, dull appearance, similar to charcoal.

Question 6. Generally, metallic oxides are basic in nature, and non-metallic oxides are acidic in nature. The solution of which of the following oxides in water will change the colour of blue litmus to red?

• Sulphur dioxide 
• Magnesium oxide 
• Iron oxide 
• Copper oxide

Answer 6: The correct option is A.

Explanation:

The oxides of metal are basic; in other words, they react with the acids to form salt and water. Metal oxides react to various inorganic acids like HCl to give salts and water. Thus, the nature of the metal oxides is basic rather than acidic or neutral. In the case of nonmetals, they are acidic to form acids when they dissolve in water. Sulphur dioxide dissolved in water can be tested with litmus paper.

SO2+ 2H2O → H2SO4 + 2H.

Sulphuric acid is an acid that turns blue litmus to red.

Question 7. Paheli prepared a blue-coloured solution of copper sulphate in beaker A and placed an iron nail in it. Boojho prepared a yellowish-green solution of ferrous sulphate in beaker B and placed a copper wire in it. What changes will they observe in the two beakers after an hour?

Answer 7:

Iron is in general more reactive than copper, and thus it displaces copper from its respective salt solution. In beaker A, copper’s reddish brown layer may deposit on the surface of the iron nail, and copper sulphate’s blue colour solution will result in yellowish green because the process forms into iron sulphate. In beaker B, there’s no change because the less reactive property of copper is not able to displace iron from its ferrous sulphate solution.

Fe(s)Iron+ CuSO4(aq)→FeSO4(aq) +Cu(s)Copper

Fe usually tends to displace the Cu from the CuSO4 solution in beaker A, which happens because Fe is more reactive than Cu. As a result, in beaker A a reddish-brown layer of copper will get deposited on the iron nail, and the blue-coloured solution will become yellowish green due to the formation of FeSO4​.

Cu(s)(Copper)+FeSO4(aq)

In beaker B, no reaction will occur as Cu, less reactive, cannot displace Fe from the FeSO4​ solution. Hence, the given solution will remain yellowish-green as it was before in colour due to no reaction.

Hence, the changes mentioned above are changes that will be observed in the two beakers after an hour.

Question 8. Write about some applications of metals.

Answer 8:

Metal in the subject of chemistry is defined as an element that can easily form positive ions known as cations and tends to form metallic bonds. These metals are distinguished by their chemical and physical properties, such as malleability, ductility, ionisation and bonding properties.

Metals are used in daily life for various purposes:

• Transportation like cars, trucks, trains, ships, and aeroplanes build materials containing metals.
• Aerospace – unmanned, human-crewed rockets and space shuttle are created using metals.
• Electronic devices require conductors like TV, stereo, radio, calculators, security devices, computers, etc. In our daily life applications, we use such gadgets.
• Communications like satellite communication depend on a tough but also light metal shell. Metals are persistent and resistant; the satellites are there in space for years and hence are not affected or eroded.
• Food preservation and processing in the microwave and conventional ovens, refrigerators and freezers are made of metals that adequately keep our foods. This application of metals in our daily life is huge and unconditional.
• Construction of nails in the conventional lumber construction and structural steel in other buildings also uses various unknown metals.
• Biomedical applications like artificial replacement for joints and other prostheses, metal rods, wires and metal plates are used inside the human body.
• Electrical consumption, power production and distribution like in boilers, generators, turbines, transformers, nuclear reactors, power lines, oil wells, and pipelines also use metals.
• Farming: tractors, planters, combines, etc., are made of metals.
• Household products and various goods like ovens, dish and clothes washers, blenders, pumps, vacuum cleaners, lawnmowers and trimmers, water heaters, heating/cooling, plumbing, etc., are made of metals. The use of metals in our daily lives is enormous and advantageous.

Question 9. Fill in the blanks to complete the following paragraph. 

The name of the product formed in the reaction of sulphur and ______ is sulphur dioxide gas. When sulphur dioxide is dissolved in _______, sulphurous acid is formed. The sulphurous acid turns ______ litmus paper to ______. Generally oxides of ________ are acidic in nature.

After completing the paragraph, write two questions which you can raise based on this information.

Answer 9:

The name of the final product formed between the reaction of sulphur and oxygen is sulphur dioxide gas. When sulphur dioxide gas is dissolved in water, we get sulphurous acid. The sulphurous acid will turn the blue litmus paper into red colour. The oxides of non-metals are usually acidic in nature.

The following questions can be asked-

(i) What is the nature of oxides?

(ii) Which gas is formed when the sulphur reacts with oxygen?

Question 10. Write about the chemical properties of nonmetals.

Answer 10:

• Chemical properties of nonmetals:

A nonmetal in chemistry can be defined as a chemical element that generally gains electrons when reacting with a metal in a chemical reaction. It tends to form an acid if combined with oxygen and hydrogen. The nonmetals display more variety in colour and state in comparison to metals. Nonmetals usually react with oxygen to form non-metallic oxides, which are acidic in nature. Sulphur interacts with oxygen to produce sulphur dioxide gas, as can be seen. When this is dissolved in the water, sulphurous acid is produced, which causes the blue litmus to turn red, showing that it is acidic in nature. Nonmetals do not usually react with water, although they can be reactive in air. When exposed to the oxygen present in the air, phosphorus in water becomes highly reactive. In terms of appearance, nonmetals react with any of the acids.

Question 11. A doctor prescribed a tablet to a patient suffering from iron deficiency. The tablet does not look like iron.

Answer 11:

Oral iron is given as ferrous sulphate or ferrous gluconate or the amino acid chelate tablets. Tablets cannot look alike iron but contain iron metal in different forms to supplement the respective deficiency. Iron supplements, also called iron salts and also iron pills, are a number of iron formulations that are used to treat and prevent iron deficiency including common iron deficiency anaemia.

• Ferrous salts (ferrous sulphate, ferrous fumarate, and ferrous gluconate) are the best-absorbed iron supplements available. They are often considered the standard compared with other iron salts.

Question 12. Paheli bought a statue made of copper. To her surprise, it acquired a dull green coating after a couple of months. Explain the reason.

Answer 11:

Copper acquires a light green coating when kept for a few months:

• Upon exposure to air in the atmosphere, the copper metal gains a dull green colour on its surface due to the corrosion of copper.
• Copper metal, upon exposure to the atmosphere, form a mixture of hydroxide and carbonate copper, also called basic carbonate.
• This mixture is obtained by the reaction of the metallic copper with the moisture present in the air, which contains oxygen gas and carbon dioxide.
• Due to the formation of these compounds, the surface of metallic copper is covered with a green layer containing Copper hydroxide and carbonate.
• The balanced chemical reaction for the conversion of copper into a mixture of hydroxide and carbonate of copper can be given as 

2Cu(s) Copper+ H2O(l) Water+ CO2 (g)Carbon dioxide+ O2 (g)Oxygen→ Cu(OH)2 (s)Copper hydroxide+ CuCO3(s)Copper carbonate

This is why copper acquired a dull green coating after a couple of months.

Benefits of Solving Important Questions Class 8 Science Chapter 4

Important Questions Class 8 Science Chapter 4 are explained in simple steps. The students easily understand these explanations and clear all doubts at once. Science Class 8 Chapter 4 important questions will make learning the subject interesting and fun. Preparing the solved questions will help with homework and exams as well. Extramarks aims to provide students with easy exam preparation and also complete homework. The solution provided will help to solve questions related to this chapter. Metal and nonmetal Class 8 is an easy and scoring chapter.

To obtain a good score in the CBSE examinations, students must understand the topics thoroughly and practise the questions in every chapter. By practising MCQs, short answers, medium answers, and long answer questions provided with step-by-step solutions, students will get well versed with the question pattern and mark the weightage of the chapter. Furthermore, the benefits of referring to Important Questions Class 8 Science Chapter 4 are:

• The questions are prepared after analysing questions in the CBSE examination and past question papers.
• The team has handpicked the majority of important topics from the chapter after a good analysis of the entire theory and the key takeaways that the student is required to know.
• The NCERT textbooks and guidelines are strictly followed so the student can clear the CBSE examination easily.
• The questions are collated from various sources, including NCERT Textbooks, CBSE Sample papers, CBSE Extra questions, NCERT Exemplars, past years’ question papers and other sources.
• By practising these advanced levels of questions thoroughly through Important Questions Class 7 Science Chapter 4, students not only brush up on the concepts thoroughly but also analyse their shortcomings and overcome them before facing the board exams.

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• NCERT books
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• Important formulas 
• CBSE extra questions