Metals and Non-metals

Exercise

Question 1

Name a metal:

(a) that is the most malleable

(b) that is brittle

(c) as precious as gold

(d) that can be cut with knife

(e) used in making electric cables

(f) used as a thermometric liquid

(g) that is the best conductor of electricity

Answer

(a) Gold

(b) Zinc

(c) Platinum

(d) Sodium

(e) Copper

(f) Mercury

(g) Silver

Question 2

Name a non-metal that is:

(a) a good conductor of heat and electricity

(b) hardest naturally occurring substance

(c) used to kill germs in water

(d) lustrous

(e) used for filling into electric bulbs

(f) used for cancer therapy

(g) liquid at room temperature

Answer

(a) Graphite (a form of carbon)

(b) Diamond (a form of carbon)

(c) Chlorine

(d) Iodine

(e) Argon

(f) Radon

(g) Bromine

Question 3

Mention two uses of the following metals and non-metals:

(a) Iron

(b) Aluminium

(c) Gold

(d) Oxygen

(e) Iodine

Answer

(a) Iron is used for:

1. Construction of power transmission towers.
2. Making pipes, tanks, cylinders, nails, agricultural tools, railings, wire meshes etc.

(b) Aluminium is used for:

1. Making utensils, cans for drinks, furniture, window frames etc.
2. Packaging foodstuffs and wrappers of medicines in the form of aluminium foil.

(c) Gold is used for:

1. Making jewellery and gold coins.
2. In dentistry to fill in teeth cavities(in form of alloy with silver).

(d) Oxygen is used for:

1. Breathing and respiration, in hospitals oxygen cylinders are used for serious patients to help them in breathing.
2. It is essential for combustion.

(e) Iodine is used for:

1. Making photographic films in the form of potassium iodide.
2. Making tincture of iodine and iodex which are used as an antiseptic and pain reliever respectively.

Question 4a

Give reasons:

Magnesium is used in fireworks.

Answer

Magnesium burns with a dazzling light so it is used in fireworks.

Question 4b

Give reasons:

Aluminium is used in making aircrafts.

Answer

Aluminium is light and when mixed with other metals like Cu, Mg, Mn it becomes stronger so it is used in making aircrafts.

Question 4c

Give reasons:

Copper is used in making electric cables.

Answer

Copper is highly ductile and is a very good conductor of heat and electricity, so it is used in making electric cables.

Question 4d

Give reasons:

Graphite is used in the leads of pencils.

Answer

Graphite is soft and its layers slip to marks paper black so it is used in the leads of pencils.

Question 4e

Give reasons:

Impure diamond is used to cut glass.

Answer

Diamond is the hardest substance so it is used to cut glass.

Question 4f

Give reasons:

Gold is mixed with copper and nickel.

Answer

Gold is the most malleable metal and is very soft. To make it harder and cheaper gold is mixed with copper and nickel.

Question 4g

Give reasons:

Tungsten is used in electric bulbs.

Answer

It can withstand high temperature and has highest melting point so it is used in electric bulbs.

Question 5

Name the metals present in the following alloys:

(a) Brass

(b) Bronze

(c) Duralumin

(d) Stainless steel

Answer

(a) Copper, zinc

(b) Copper, tin

(c) Aluminium, manganese, magnesium, copper

(d) Iron, chromium, nickel

Question 6

Give four differences between metals and non-metals with reference to their:

(a) Melting point and boiling point

(b) Conductivity of heat and electricity

(c) Malleability

(d) Solubility in water.

Answer

(a) Metals have high melting point and boiling point whereas non-metals have low melting point and boiling point.

(b) Metals are good conductors of heat and electricity but non-metals are bad conductors of heat and electricity.

(c) Metals are mostly malleable while non-metals are not malleable.

(d) Metals are insoluble in water while non-metals can be soluble or insoluble in water.

Question 7

What are metalloids?

Answer

Metalloids are the elements which show some properties of metals and some properties of non-metals. Examples: Silicon(Si), Germanium(Ge), Antimony(Sb).

Question 8

Give two uses of:

(a) Silicon

(b) Antimony

(c) Tungsten

(d) Germanium

Answer

(a) Two uses of silicon are:

1. It is used to make water proof materials like bags, umbrellas, raincoats etc.
2. Highly pure silicon is used in making microchips for computers, transistors, solar cells, rectifiers.

(b) Two uses of antimony are:

1. It is used in electric industry to make semiconductor devices.
2. It is used in printing presses as type metal.

(c) Two uses of tungsten are:

1. It is used in making filament of bulb.
2. It is used in making electrodes.

(d) Two uses of Germanium are:

1. It is used as a semi-conductor.
2. It is used as a transistor in many electronic appliances when mixed with arsenic, gallium, antimony, etc.

Objective Type Questions

Question 1

Fill in the blanks:

(a) The most ductile metal is ............... .

(b) A metal stored in kerosene oil is ............... .

(c) Tungsten metal is a good conductor of ............... .

(d) ............... is a soft metal.

(e) ............... is the hardest compound known to us.

(f) A non-metal used to purify water is ............... .

(g) A metal that gives dazzling effect to crackers when they explode is ............... .

(h) A chemical compound that makes up the striking heads of match sticks is ............... .

Answer

(a) Silver

(b) Sodium

(c) electricity

(d) Pure gold

(e) Silicon carbide

(f) Chlorine

(g) Magnesium

(h) Phosphorous sulphide

Question 2

Match the following:

Answer

Question 3

Write True or False for the following statements:

(a) Silver is used to make electric cables.

(b) Iodine acts as an antiseptic in the form of tincture of iodine.

(c) Sodium can be cut with a knife.

(d) Antimony is a metal.

(e) Sand is an oxide of silicon.

Answer

(a) False
Correct Statement — Copper is used to make electric cables.

(b) True

(c) True

(d) False
Correct Statement — Antimony is a metalloid.

(e) True

Question 4a

The noble gas used in advertising signboards is:

1. Helium
2. Neon
3. Argon
4. Krypton

Answer

Neon

Reason — Neon emits a coloured light when a high voltage current is passed through it, so it is used in advertising signboards.

Question 4b

A metal with melting point less than 50°C is:

1. Gallium
2. Iron
3. Gold
4. Aluminium

Answer

Gallium

Reason — Gallium changes into liquid above 30°C i.e. even when placed on palm of hand.

Question 4c

A metal which is neither ductile nor malleable is:

1. Copper
2. Silver
3. Zinc
4. Aluminium

Answer

Zinc

Reason — Zinc is neither ductile nor malleable but it is brittle.

Question 4d

Rust is a hydrated oxide of iron which is:

1. Reddish brown
2. Green
3. White
4. Black

Answer

Reddish brown

Reason — Iron when exposed to moist air forms a reddish brown layer known as rust on its surface. Rust is hydrated ferric oxide.

Question 4e

Aluminium is not used to make:

1. Foils
2. Wires
3. Fireworks
4. utensils

Answer

Fireworks

Reason — Aluminium is used to make foils, wires, utensils. Magnesium is used in fireworks as it burns with dazzling light but aluminium does not.

Question 4f

A metalloid used in the manufacture of microchips used in computer is:

1. Antimony
2. Germanium
3. Silicon
4. Arsenic

Answer

Silicon

Reason — Highly pure Silicon is used in the manufacture of microchips used in computer.

Question 4g

A metalloid used to make glass:

1. Sulphur
2. Germanium
3. Silicon
4. Antimony

Answer

Silicon

Reason — Sand which is silicon dioxide, is the principal ingredient of glass.