Explore topic-wise InterviewSolutions in .

The five uses of metals are given below: 

1. Used for making machinery and heavy equipment. Ex-Iron. 

2. Used in making electric wires because it is a good conductor of electricity. Excopper 

3. Used to make thin foils for packaging medicines, chocolate, and food items. This is because it provides a complete barrier to light, oxygen, moisture, and bacteria. 

4. Used in the manufacture of many products such as paints, rubber, cosmetics, pharmaceuticals, plastics, inks, soaps, batteries, textiles and electrical equipment. 

5. Mercury is a liquid metal and is used for making thermometers. It is liquid at room temperature and is a very good conductor of heat.

The five uses of non-metals are given below: 

1. Used for making fire crackers. 

2. Oxygen is an essential non-metal for life. It helps in maintaining life and is inhaled during breathing. 

3. Chlorine is used in water purification process to make drinking water supply germ-free. Chlorine kills pathogens such as bacteria and viruses by breaking the chemical bonds in their molecules. 

4. Iodine is a non-metal. It is used to make purple coloured solution which is applied on cuts and wounds as an antiseptic. 

5. Nitrogen is also a non-metal is used to make fertilizers and explosives.

Copper, gold and silver are Malleable and ductile because these are metals. The property of metals which allows metals to be hammered into thin sheets is called Malleability. Due this unique property, metals can be flattened into thin sheets by hammering and rolling. The property of metals which enables them to be drawn into wires is called Ductility. Due to this property metals can be stretched without breaking and drawn into thin wires. All of these metals can be used to make wires and sheets.

Sulphur, phosphorous and carbon are brittle. These are nonmetals and cannot be rolled into wires or drawn into sheets.

Element A is a nonmetal. Since, it is soft and brittle in nature.

Element B is a metal because it is malleable and ductile and it also conducts electricity. The property of metals which allows metals to be hammered into thin sheets is called Malleability. Due this unique property, metals can be flattened into thin sheets by hammering and rolling. The property of metals which enables them to be drawn into wires is called Ductility. Due to this property metals can be stretched without breaking and drawn into thin wires. All of these metals can be used to make wires and sheets.

When copper vessel is exposed to moist air for a long time it develops a green layer on its surface. Copper corrodes by oxidation in which it reacts with oxygen in the air to form copper oxide. Copper oxide then combines with carbon dioxide to make copper carbonate, which gives it a green colour. This process is called corrosion of copper.

The green material is a mixture of copper hydroxide (Cu(OH)₂) and copper carbonate (CuCO₃). 

The following is the reaction 2Cu + H₂O + CO₂ + O₂ → Cu (OH)₂ + CuCO₃ moist air.

(a) Metals react with water to produce hydrogen gas. Sodium reacts with water to form sodium hydroxide and hydrogen gas. Sodium is a highly reactive metal. It even reacts with the moisture present in air. The reaction of sodium with water is highly exothermic in nature. It produces a lot of heat energy and this heat energy can cause the hydrogen gas produced during the reaction, to catch fire. In order to keep it safe, sodium metal is stored in kerosene.

(b) Metals reacts with water to form metal hydroxides and hydrogen gas. These metallic hydroxides are basic. Sodium reacts with water to form sodium hydroxide and hydrogen gas. Sodium hydroxide is basic in nature.

(i) Gold – (d) Jewellery 

Gold is used to make jewellery. This is because these metals are attractive due to their luster and rarity. These metals do not tarnish or react with air. 

(ii) Iron – (e) Machinery 

Iron is a very strong metal. It is highly malleable and ductile and hence, can be changed into desired shapes. 

(iii) Aluminium – (c) Wrapping food 

Aluminium is used to make thin foils for packaging medicines, chocolates and food items. This is because it provides a complete barrier to light, oxygen, moisture and bacteria. 

(iv) Carbon – (f) Fuel 

Carbon can be used as a fuel in the form of coke and charcoal. 

(v) Copper – (b) Electric wires 

The property of metals which enables them to be drawn into wires is called Ductility. Due to this property metals can be stretched without breaking and drawn into thin wires. 

For example: Aluminium and copper are examples of highly ductile metals. 

(vi) Mercury – (a) Thermometers 

Mercury is used for making thermometers. It is liquid at room temperature and is a very good conductor of heat. Even a slightest change in temperature can be noted by using mercury.

(a) Carbon and Sulphur will form acidic oxides. Nonmetals react with oxygen to form nonmetallic oxides. These oxides differ from metallic oxides because they are acidic in nature. Nonmetallic oxides react with water to form acids. Therefore, oxides of sulphur and carbon i.e. sulphur dioxide and carbon dioxide are acidic in nature.

(b) Sodium and magnesium oxides will be basic in nature. Metals react with oxygen to form metallic oxides. These metallic oxides are basic because they react with water to form bases.

1. The property of metals which allows metals to be hammered into thin sheets is called Malleability. Due this unique property, metals can be flattened into thin sheets by hammering and rolling. 

For example: aluminium due to its high ductility, it can be changed into thin sheets to make aluminium foil. 

2. The property of metals which enables them to be drawn into wires is called Ductility. Due to this property metals can be stretched without breaking and drawn into thin wires. 

For example: Copper metal is used for making electric wires because it is highly ductile in nature. 

3. Metals have quality to reflect light. As a result, metals are lustrous in nature. It makes metals attractive due to their luster and rarity. Hence, metals like, gold and silver are used to make jewellery. These metals do not tarnish or react with air. 

4. Metals are sonorous because they produce a unique sound when something hard strikes their surface. As a result, metals are used in making bells or gongs.

B. sodium

Phenolphthalein is an indicator used in acid-base titrations. It turns colorless in acidic solutions and pink in basic solutions. Sodium is a metal which reacts with water to form sodium hydroxide, which is a base. Hence, phenolphthalein turns the solution pink.

C. potassium 

Potassium is a metal. Metallic oxides are basic in nature.

(a) This reaction will not occur. Zinc is more reactive than copper. Copper will not be able to replace zinc from zinc sulphate solution. A more reactive metal can replace a less reactive metal, but a less reactive one cannot replace a more reactive metal. On the other hand, if we take copper sulphate solution and zinc, then zinc will be able to replace copper from copper sulphate solution. Hence, the above reaction will not take place.

(b) A more reactive metal can replace a less reactive metal, but a less reactive one cannot replace a more reactive metal. This reaction will take place. In this case, Iron is more reactive than copper. In a solution of copper sulphate, iron will react and will be able to displace copper from its solution. In this reaction, iron will change into iron sulphate and copper metal will be produced.

Magnesium is a metal. Metals react with oxygen to form metallic oxides. These Hence, Magnesium oxides are basic in nature. On the other hand, nonmetals react with oxygen to form nonmetallic oxides. These oxides differ from metallic oxides because they are acidic in nature. Nonmetallic oxides react with water to form acids. Therefore, Sulphur dioxide is acidic in nature. Magnesium oxide is basic in nature.

An element which forms oxide which is acidic in nature is a non-metal. This is because nonmetallic oxides react with water to form acids.

D. brittle 

Sulphur is a nonmetal. It cannot be drawn into wires or changed into sheets. It is very soft and hence, is brittle in nature.

When sulphur dioxide is dissolved in water, then it forms sulphurous acid (H₂SO₃).

Explanation: Metals react with oxygen to form metallic oxides. These metallic oxides are basic in nature because they react with water to form bases. On the other hand, non-metals react with oxygen to form non-metallic oxides and these oxides differ from metallic oxides because they are acidic in nature. Also, non-metallic oxides react with water to form acids.

Sulphur is non-metal, and sulphur dioxide (SO₂) is acidic in nature. Thus, it reacts with water to form sulphurous acid (H₂SO₃ or H₂O.SO₂)

The chemical reaction is: SO₂ + H₂O → H₂SO₃

A. carbon 

Carbon is a nonmetal. Nonmetals form oxides which are acidic in nature. Oxide of carbon is acidic.

B. brittleness 

Brittleness is not a characteristic property of Iron because it is a metal. Malleability, ductility, and sonorousness are the properties of metals.

C. silicon 

Silicon is a metalloid. The elements whose properties are intermediate between the properties of metals and nonmetals are called Metalloids.

B. silver 

Silver is least reactive will not produce hydrogen gas with sulphuric acid.

Copper does not react with dilute hydrochloric acid because it is below hydrogen in the reactivity series of metals.

When aluminium foil reacts with sodium hydroxide, sodium aluminate is formed. Metals react with dilute acids to form metallic salts and hydrogen gas. 

For example: Aluminium foil reacts with dilute hydrochloric acid to produce aluminium chloride and hydrogen gas.

The balanced chemical equation for the reaction is:

2Al(s) + 6HCl(aq) 2AlCl₃(aq) + 3H₂(g). 

Aluminium is an amphoteric metal. It reacts with both acids and bases. The reaction is highly exothermic and produces a lot of heat. There is rapid evolution of hydrogen gas during this reaction.

Aluminium is highly malleable and ductile. Due to this property, aluminium is used in the production of utensils and wire. Aluminium is a good conductor of heat which makes it ideal for making utensils.

Food stuff like orange juice, pickles, chutney and curd are acidic in nature. Iron and aluminium are highly reactive metals. If any of this stuff is stored in iron or aluminium container the acid inside these food stuffs will react with iron or aluminium to produce toxins. 

Hence: we cannot store foodstuffs like orange juice, pickles, chutney and curd not be kept in iron or aluminium containers.

List of 5 items that float on water:

1. Paper 

2. Wood 

3. Wax 

4. Ice 

5. Oil

1. First, this mixture should be sieved through the sieve of small holes. 

2. Then rice will remain in the sieve and mustered seeds along with salt will come down. 

3. Now take the mixture of mustard seeds and salt in a vessel and add water to it. 

4. Let the salt dissolve in the water. 

5. Filter it into another vessel using a cloth or filter paper. 

6. Mustered seeds will remain on the cloth/ filter paper and saltwater goes down into the vessel. 

7. Heat the saltwater till the water completely get evaporate living behind the salt crystals in the vessel. 

8. Thus by using three methodssieving, filtration and crystallization, he can separate mustered seeds, rice and salt from their mixture.

1. Aim: 

Lighting a candle without touching its wick. 

2. 

a) Oxygen, 

b) carbon dioxide 

3. Yes. It catches fire, as there is vapour around the wick. 

4. Yes, the smoke is the gas of wax.

1. Sugar takes the shape of the container. So one group of students concluded that sugar is a liquid. 

2. Razia, a student, took a single crystal of sugar and one drop of water and declared that sugar is solid while water is a liquid. 

3. As sugar crystals are very small they assumed the shape of the container. Razia argued that sugar crystal has a definite shape and can be held independently. 

4. She showed that a drop of water has no definite shape and is not possible to hold it independently as is done with the sugar crystal. 

5. This sweet dilemma is thus solved.

(a) sulphur dioxide

The physical properties on the basis of which metals can be distinguished from non-metals are:

(i) Hardness- Metals are hard while non-metals are soft.

(ii) Lustre- Metals are lustrous while non-metals are not lustrous.

The correct answer is : oxygen gas

When a piece of sodium is dropped in water then it reacts vigorously with water to form sodium hydroxide with the evolution of hydrogen gas in the form bubbles. This hydrogen gas catches fire and a large amount of heat releases. This is a highly exothermic reaction. The solution will be basic in nature because sodium hydroxide is formed.

2Na + 2H₂O→2NaOH + H₂

(i) When metals come in contact with air and water then rusting takes place. In iron, rusting is a process in which iron is oxidised into ferric oxide (Fe₂O₃).

(ii) The presence of impurities in the iron like water vapours, acids, salts and carbon dioxide also responsible for rusting.

(iii) Iron does not rust in pure water which is free from dissolved salts.

(iv) Metals like chromium, zinc and magnesium prevent rusting. So zinc is used to galvanise the iron to prevent rusting of iron.

When sulphur dioxide reacts with water then sulphurous acid (H₂SO₃) is produced.

SO₂ + H₂O→ H₂SO₃

(a) (i) Malleability- Malleability is a property of metals in which metals can be beaten into sheets.

Example- Gold and aluminium

(ii) Ductility- Ductility is a property of metals in which metals can be drawn into wires.

Example- Copper

(b) Diamond is a non-metal which is very hard. Diamond is an allotrope of carbon.

Diamond is a non-metal which is very hard. Diamond is an allotrope of carbon.

When metals react with dilute acids then hydrogen gas is produced. This hydrogen gas burns with a pop sound.

Na + dil.HCl→ NaCl + H₂

(a) When metals combine with oxygen then metal oxides are formed which are basic in nature because they dissolve in water to form metal hydroxides which are basic in nature. These metal hydroxides release OH^- ions.

(b) When non-metals combine with oxygen then non-metal oxides are formed which are acidic in nature because these react with water to form acids or with bases to form salts.

(1) Iron – It is used to make doors and windows.

(2) Copper – It is used to make electric wires.

(3) Gold – It is used to make ornaments.

(4) Silver – It is also used to make ornaments.