Explore topic-wise InterviewSolutions in .

(i) True.

(ii) False. (Ornaments are made from 22 carat gold.)

(iii) True.

1. The property due to which a substance can be hammered (or rolled) into a thin sheet without cracking is called malleability. 

2. Metals are malleable. Thus, a metal can be hammered to form a thin sheet.

Correct option is (b) Antimony

Correct option is (c) Br

Correct option is (a) Hg

1. Non-metals lack lustre. 

2. As non-metals are brittle, they are not malleable. 

3. They are not ductile. 

4. Non-metals are poor conductors of heat and electricity. 

5. At ordinary temperature, non-metals are in the solid or gaseous state. (Exception: Bromine is liquid.) 

6. Non-metals have low density in the solid state.

1. Metals have a lustre. 

2. Metals are malleable. They can be beaten into thin sheets. 

3. Metals are ductile. They can be drawn into wires. 

4. They are good conductors of heat and electricity. 

5. At ordinary temperature, metals are generally solid. (Exception: Mercury is liquid.) 

6. Metals usually have high density.

The alloy brass is formed from copper and zinc and the alloy bronze is formed from copper and tin.

By applying a layer of paint, oil, grease or varnish on the surface of a metal to prevent corrosion. Also plating with noncorroding metal is done. Iron is coated with thin layer of zinc. Due to these processes the contact of metal surface with air is lost and corrosion is prevented.

Carbon and sulphur are solids at room temperature.

Iodine and diamond are lustrous in nature.

Hydrogen and oxygen are in gaseous state at room temperature.

Copper and aluminium are good conductors of electricity.

1. A reddish coloured deposit (rust) is formed on iron by reaction with oxygen gas. 

2. A greenish coloured deposit (copper carbonate) is formed on copper by reaction with carbon dioxide. 

3. A blackish coloured deposit is formed (silver sulphide) on silver. 

4. Corrosion causes damages to car bodies, bridges, iron railings, ships specially those of iron, silver articles and copper vessels.

Bromine is in liquid state at room temperature.

Sodium and potassium having low melting points and boiling points.

Uses of Noble Metals:

1. Gold, silver and platinum are used to prepare ornaments. 

2. Silver is used in medicines. (It has antibacterial property). 

3. Gold and silver are also used to make metals and few electronic devices. 

4. Platinum, palladium metals are used as catalyst.

(i) True.

(ii) False. (The metal oxides are basic in nature.)

(iii) True.

1. The metal sheets of ships are made from iron. 

2. Due to salty seawater, the metal sheets of ships get rusted and corroded. Paints contain metals like zinc or magnesium. This prevents the metal surface of the ship coming into direct contact with salty seawater. Therefore, ships are painted at frequent intervals.

Metals combine with oxygen in the ’ air to form their oxides.

Metal + Oxygen → Metal oxide

[Note: Reaction/explanation given in the screen are for better understanding of students. The same are not given in the textbook.]

When magnesium burns in air, it combines with oxygen to form magnesium oxide.

2Mg + O₂ → 2MgO

Magnesium Oxygen Magnesium oxide

1. The metals such as gold and platinum are found in nature in the form of elements. 

2. They are not affected by water, air, acids, heat and also do not take part in chemical reactions. Hence, they are called noble metals.

1. The purity of gold is measured in carats. 

2. Twenty-four carat gold is considered as gold of 100% purity. 

3. 24-carat pure gold is very soft. 100% pure gold bends easily or breaks due to pressure. Therefore, copper or silver is added to gold in the necessary proportion (while making ornaments). 

4. Generally, 22-carat gold is used in making ornaments.

Correct option is (b) 91.66%

1. 24-carat gold is considered as gold of 100% purity. 

2. 24-carat pure gold is very soft. 100% pure gold breaks due to pressure or gets bent easily. Therefore, ornaments are generally not made from 24-carat gold.

Metals: Gold, silver, aluminium and copper. 

Non-metals: Silicon, sulphur, carbon and phosphorus.

Sodium and potassium metals react with cold water.

Aluminium and iron do not react with cold water or hot water.

A metalloid used in the manufacture of microchips used in a computer is Silicon

Aluminium is not used to make Fireworks

Rust is a hydrated oxide of iron which is Reddish brown

A metalloid used to make glass Antimony

1. that is most malleable: Pure gold 

2. that is brittle: Zinc 

3. as precious as gold: Platinum 

4. that can be cut with knife : Sodium 

5. used in making electric cables: Copper 

6. used as a thermometric liquid: Mercury 

7. that is the best conductor of electricity: Silver

A metal which is neither ductile nor malleable is Zinc

Metalloids are the elements which show some properties of metals and some properties of non-metals. They all are solids. They are silicon, boron, arsenic, antimony, germanium, tellurium and polonium.

1. Brass— Copper and zinc

2. Bronze— Copper and tin

3. Duralumin— Aluminium and copper

4. Stainless steel— Iron, chromium, nickel

1. Impure diamond is used to cut glass because it is the hardest substance and can easily exert force required for cutting.

2. Pure gold is a very soft metal. It cannot be molded into ornaments so it is mixed with copper and nickel so that it becomes harder and bit cheaper also.

3. It is a shiny grey metal, in a solid state at room temperature. It can withstand high temperature because it has the highest melting point among metals. Hence, it is used in electric bulbs.

(a) Magnesium is used in fireworks because it bums with a dazzling light.

(b) Aluminium is used in making aircraft because it is light and strong. It is mixed with other metals to make it stronger.

(c) Graphite turns paper black that is why it is used in the leads of pencils.

(d) Impure diamond is used to cut glass because it is the hardest substance and can easily exert force required for cutting.

Correct option is (c) both metals and non-metals