Metals and Non-Metals Class 10

Which of the following pairs will give displacement reactions?
(a) NaCl solution and copper metal
(b) MgCl
2
solution and aluminium metal
(c) FeSO
4
solution and silver metal.
(d) AgNO
3
solution and copper metal.

Which of the following methods is suitable for preventing an iron frying pan from rusting?
(a) Applying grease
(b) Applying paint
(c) Applying a coating of zinc
(d) All of the above.

An element reacts with oxygen to give a compound with a high melting point. This compound is also soluble in water. The element is likely to be
(a) calcium
(b) carbon
(c) silicon
(d) iron.
Answer:-
It is given that the element
reacts with oxygen
to give a
high melting point
.
Hence, the element
must be very reactive
and
must
form an ionic bond
.
Ionic bonds are are formed
between electropositive metals
and
electronegative non-metals
Carbon
and
Silicon
are neither electropositive nor electronegative. They
form covalent bonds
.
So, the element can either be Calcium or Fe
It's also given that the compound is
soluble in water.
The metal
must be
an
alkali
metal.
From the given options, only
Calcium
is an alkali metal.
Therefore, the element is most likely to be
Calcium (Ca)
.
So, the correct
answer is (a)

Food cans are coated with tin and not with zinc because
(a) zinc is costlier than tin.
(b) zinc has a higher melting point than tin.
(c) zinc is more reactive than tin.
(d) zinc is less reactive than tin.

You are given a hammer, a battery, a bulb, wires and a switch.
(a) How could you use them to distinguish between samples of metals and non-metals?
(b) Assess the usefulness of these tests in distinguishing between metals and nonmetals.
Answer:-
By the given materials,
2 sets of experiments
can be
done
in order to distinguish if a given substance is metal or nonmetal.
The
Hammer
can be used to
check
the
malleability, hardness, and sonority
of a substance.
Metals are malleable
, that is, they can be broken down into thin sheets without breaking
Most
metals are hard
. They don’t break/deform when force is applied.
Metals are sonorous
. They make sounds when hit.
Non-metals
are
Brittle, soft, and not sonorous
.
A
bulb
,
wires
and a
switch
can be used to
check
the
electrical conductivity
of a substance.
A set up of a bulb, wire, 2 holders and a switch can be made as shown below.
Now, attach the substances to be tested in the holders one by one
Metals conduct electricity
. So, if the substance is metallic the
bulb will light up
when the switch is on.
Non-metals are poor conductors. The bulb will not light up
when the switch is on.

What are amphoteric oxides? Give two examples of amphoteric oxides.
Answer:-
An amphoteric compound is a
molecule or ion
that can
react both
as an
acid
and as a
base
.
Certain
metal oxides which are both acidic and basic
are called amphoteric oxides.
Example - Aluminium Oxide (Al
2
O
3
)
Similarly, ZnO is also an amphoteric oxide.

Name two metals which will displace hydrogen from dilute acids, and two metals which will not.
Answer:-
In displacement reactions,
Metals which
lie above Hydrogen
in the
reactivity series
can
displace
it
from Dilute acids
Those that lie
below
hydrogen in the reactivity series
cannot
.
Let’s look at the reactivity series:
Any of the metals in the series placed
above
Hydrogen
can displace it
from its acids.
Two such metals are -
K (Potassium)
and
Na (Sodium)
Any of the metals in the series placed
below
Hydrogen
will not be able to displace it
from its acids.
Two metals which will not displace hydrogen are -
Hg (Mercury)
and
Ag (Silver)

In the electrolytic refining of a metal M, what would you take as the anode, the cathode and the electrolyte?

Pratyush took sulphur powder on a spatula and heated it. He collected the gas evolved by inverting a test tube over it, as shown in figure below.
(a) What will be the action of gas on
(i) dry litmus paper?
(ii) moist litmus paper?
(b) Write a balanced chemical equation for the reaction taking place.

State two ways to prevent the rusting of iron.
Answer:-
Rusting of iron can be prevented by :
(1) Galvanization
In galvanisation, a sacrificial
coating of zinc
is applied
on iron
and
steel
.
Since
Zn is more reactive
than Iron, the
Zn coating reacts
with the surroundings,
leaving the Iron untouched.
It
prevents
steel and iron
from rusting
.
(2) Alloying
An alloy is a
homogeneous mixture
of 2 or more metals. In alloying ,a metal is mixed with some metal or nonmetal. This
changes
the
properties of
the
metal
.
Example
When
iron
is
mixed
with
Nickel
and
chromium
, we
get stainless steel
. This
prevents corrosion
as iron rusts but stainless steel does not.

What type of oxides are formed when nonmetals combine with oxygen?
Answer:-
When non-metals react with oxygen, they
form oxides
which are
either acidic or neutral
in nature.
For example,
1. Acidic Oxide
Carbon Dioxide
dissolves in water to form Carbonic Acid.
So,
Carbon Dioxide is acidic
in nature
2. Neutral Oxide
Carbon reacts with Oxygen in an
insufficient supply of air
to
produce Carbon Monoxide
.
It
does not react
with water.
So, it
produces neither acid nor base
with water
.
Therefore, carbon monoxide is
neutral.

Give reasons
(a) Platinum, gold and silver are used to make jewellery.
Answer:-
(a)
Platinum, gold and silver are used to
make jewellery
because
They are very
lustrous
metals.
They are the
least reactive
metals, hence they
do not corrode
easily.
They are
malleable
and
ductile
. Hence, they can be moulded into different ornaments.

Give reasons
(b) Sodium, potassium and lithium are stored under oil.
Answer:-
(b)
Sodium, potassium and lithium are
stored under oil.
Some metals
react more vigorously
like sodium and potassium.
They
catch fire
if kept
in
the
open
.
Hence,
to protect
them and
to prevent
accidental
fires
, they are
kept in kerosene oil
.

Give reasons
(c) Aluminium is a highly reactive metal, yet it is used to make utensils for cooking.
Answer:-
(c) Aluminium is a highly reactive metal, yet it is used to make utensils for cooking.
Aluminium is a highly reactive metal
It
reacts readily with oxygen
to form Aluminium Oxide
(Al
2
O
3
)
which is
very stable
.
This layer
protects
Aluminium from
further damage
or
corrosion
.
This layer of Aluminium oxide
doesn’t react with food
while cooking, that is why it is used to make utensils for cooking.

Give reasons
(d) Carbonate and sulphide ores are usually converted into oxides during the process of extraction.
Answer:-
(d) Carbonate and sulphide ores are usually converted into oxides during the process of extraction.
It is
not easy to reduce
naturally occurring
carbonate and sulphides directly
into metals.
The process involves
extra steps
and is
not commercially viable
Hence, they're first
converted into oxides
.
After an ore is converted into oxide, it is
easier to reduce
them into pure metals.

You must have seen tarnished copper vessels being cleaned with lemon or tamarind juice. Explain why these sour substances are effective in cleaning the vessels.
Answer:-
Green coating on copper is copper carbonate. It is
formed by
the
reaction of copper with
carbon dioxide
,
moisture
and
oxygen
in the atmosphere.
Copper is a
metal
. Hence, it
forms
a
basic oxide
.
So,
Copper oxide is basic
in nature.
Lemon
and
tamarind juice
are
acidic
in nature.
Lemon / tamarind juice reacts with the basic copper oxide to
neutralise
it,
forming salt
and
water
and
thus cleaning
them.

Differentiate between metal and non-metal on the basis of their chemical properties.
Answer:-
Metals
Non-Metals
Metals react with Oxygen to
form basic oxides
.
Non- Metals react with Oxygen to
form acidic or neutral oxides
.
Most metals
displace Hydrogen
from dilute acids.
Non-metals
do not react
with dilute acids.
Only a few metals
combine with Hydrogen
to
form Ionic Hydrides.
. (Eg: Na, Ca)
Non-Metals
combine with Hydrogen
to
form Covalent hydrides
.
Most metals
displace Hydrogen from water/steam
to form Metal Hydroxides.
Usually, non-metals
do not react with water/steam
.
Metals react with Cl to
form Ionic Chlorides
Non-metals react with Cl to
form Covalent Chlorides

A man went door to door posing as a goldsmith. He promised to bring back the glitter of old and dull gold ornaments. An unsuspecting lady gave a set of gold bangles to him which he dipped in a particular solution. The bangles sparkled like new but their weight was reduced drastically. The lady was upset but after a futile argument the man beat a hasty retreat. Can you play the detective to find out the nature of the solution he had used?
Answer:-
Gold
is one of the least reactive metals, hence it
does not react with acids
and other substances which can help in cleansing/shining of the gold metal.
Aqua Regia
is a mixture of concentrated HNO3 and concentrated HCl.
It is used by jewellers and blacksmiths for
dissolution of gold
.
It is a
very corrosive
liquid.
It
removes the top corroded layer
of gold and returns its shine.
When the gold bangles were dipped in it, the
upper layer of the gold
would’ve
dissolved
in it, thus resulting in loss of mass of the bangles.

Give reasons why copper is used to make hot water tanks and not steel (an alloy of iron).
Answer:-
We know that
Iron
is a
reactive metal
. Its alloy,
steel
, is also
relatively reactive
.
Copper,
on the other hand, lies
low
on the
reactivity series
.
Hence,
Steel would react with hot water
to form iron oxide and hydrogen gas.
Iron
is
more prone to rusting
than Copper.
Copper
is a
better conductor of heat than steel
, hence it’s more suitable for making hot water tanks.

Q1) Give an example of a metal which
(i) is a liquid at room temperature.
(ii) can be easily cut with a knife.
(iii) is the best conductor of heat.
(iv) is a poor conductor of heat. ?

Explain the meanings of malleable and ductile.

Why is sodium kept immersed in kerosene oil?

Write equations for the reactions of
(i) iron with steam

Write equations for the reactions of
(ii) calcium and potassium with water

Samples of four metals A, B, C and D were taken and added to the following solution one by one. The results obtained have been tabulated as follows.
Use the Table above to answer the following questions about metals
A, B, C and D.
(i) Which is the most reactive metal?
(ii) What would you observe if B is added to a solution of Copper(II) sulphate?
(iii) Arrange the metals A, B, C and D in the order of decreasing reactivity.
Answer:-
(i)
According to the
reactivity series
, among the 4 salts given,
Zinc Sulphate is the most reactive
.
Since
no metals react
with it, we consider the
next most reactive solution, Iron (II) Sulphate
.
Since
only B is able to displace Iron
from Iron (II) Sulphate, it is the
most reactive
among A,B,C,D
(ii) What would you observe if B is added to a solution of Copper(II) sulphate?
B is more reactive than Fe, which in turn is more reactive than Cu.
And so,
B will displace Cu
from its salt solution.
(iii) Arrange the metals A, B, C and D in the order of decreasing reactivity.
Let us go in order of most reactive to least reactive salt solutions.
Zinc
solution is the most reactive salt solution here. But
no metal reacts with it
.
B
is the most reactive element as it is able to displace
Iron from its salt solution
.
A
is able to displace
copper from its salt solution.
C
is able to displace
Silver from its salt solution.
D
is the least reactive element, since it
does not react at all
.
So,
The reactivity series in decreasing order is given as
B>A>C>D

Q.4 ) Which gas is produced when dilute hydrochloric acid is added to a reactive metal? Write the chemical reaction when iron reacts with dilute H
2
SO
4
.

What would you observe when zinc is added to a solution of iron(II) sulphate? Write the chemical reaction that takes place.
Answer:-
When Zinc is added to a solution of Iron (II) sulphate, a
displacement reaction
takes place.
Zinc
being a more reactive metal than Iron (as zinc lies about iron in the reactivity series),
will replace iron
from its salt solution.
The reaction produces
Zinc sulphate + Iron.
The Iron settles as a
grey precipitate
and a
colourless solution
of zinc is formed.
The reaction can be given as,

(i)
Write the electron-dot structures for sodium, oxygen and magnesium. Show the formation of Na
2
O and MgO by the transfer of electrons.
Answer (i)
The two sodium atoms lose 1 electron each to form 2 sodium ions (2Na
+
).
The oxygen atom forms an oxide ion (O
2-
) by gaining 2 electrons, one from each sodium atom.
Na and O hence form an ionic compound Sodium Oxide (Na
2
O).

(ii)
What are the ions present in these compounds?
Answer (ii)
The two sodium atoms lose 1 electron each to form 2 sodium ions (2Na
+
).
The oxygen atom forms an oxide ion (O
2-
) by gaining 2 electrons, one from each sodium atom.
Na and O hence form an ionic compound Sodium Oxide (Na
2
O).
(ii)
The ions present in sodium oxide compound (Na
2
O) are : Sodium ions (
Na
+
) and oxide ions.(
O
2-
)
Magnesium oxide (MgO) is formed of
Mg
2+
and
O
2-
ions.

Why do ionic compounds have high melting points?
Answer:-
Ionic compounds are
closely packed structures
made up of
ions of opposite charges
(cations and anions).
The
large amounts of intermolecular force of attraction
lead to
strong ionic bonds.
A
large amount of energy is needed
to overcome these forces
.
That is why the melting point of ionic compounds is very high.

Define the following terms.
(i) Mineral
(ii) Ore
(iii) Gangue
Answer:-
(i)
Minerals
Elements or compounds
which
occur naturally
in earth's crust are called Minerals.
These minerals
may or may not contain metals.
Example: Salt,Clay Marble.
(ii) Ore
Those
minerals
which
contain
a
very high percentage
of a
particular metal
from which
metal
can be profitably
extracted
is called ores.
Example
Aluminium Metal
is extracted from
Bauxite Ore
Iron Metal
is extracted from
Hematite Ore
Sodium Metal
is extracted from
Rock Salt
(iii) Gangue
Unwanted impurities
present
in
the
ore
is called Gangue.
Example -
Soil, Sand, Rocky materials.

Name two metals which are found in nature in the free state.

What chemical process is used for obtaining a metal from its oxide?

Metallic oxides of zinc, magnesium and copper were heated with the following metals.
In which cases will you find displacement reactions taking place?

Which metals do not corrode easily?
Answer:-
Those metals which
do not react actively
, tend to
not corrode
easily.
That is,
less reactive metals
, which lie near the bottom of the reactivity series, do not react easily.
These metals are
Silver, Gold, Platinum.

What are alloys?
Answer:-
An alloy is a
homogeneous mixture
of 2 or more metals or one metal and one non metal.
Examples
of some alloys are Brass, Bronze, Solder, 22 Carat Gold, Stainless steel.
Brass
- comprises 80% copper and 20% Zinc. It is not a good conductor of electricity.
Bronze
- comprises 90% copper and 10% tin. Bronze is not a good conductor of electricity, despite having copper as its constituent.
Solder
- comprises 50% lead and 50% tin. It has a lower melting point than lead and tin hence it is used for welding wires together.
Stainless steel
- comprises iron and nickel/ chromium. Iron rusts but stainless steel does not rust.