Class 10 Science: Chapter
3, Metals and Non-metals
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CBSE Questions | CBSE Guess
Question 1: What are electrovalent or Ionic compounds?
Answer: The compounds formed by
the transfer of electrons from a metal to a non-metal are known as
electrovalent or Ionic compounds. For example, NaCl is an electrovalent
compound.
Question 2: What is the reason for difference in reactivity of metals?
Answer: Metals are those elements which can loose
electrons easily. The reactivity of a metal will depend upon how easily the
metal can loose electron and form positively charged ion. Hence, we find some
metals are less reactive whereas other metals are more reactive. (Hydrogen and
Helium have one and two electrons respectively but still they are non-metals
because they cannot loose electrons easily).
Question 3: Why do we find most of the ores in oxide form?
Answer: The earth's crust is the
major source of ores. Most of the ores of metals are found as oxides because
oxygen is a very reactive element and is highly abundant on the earth.
Question 4: What are metalloids?
Answer: Metalloids are those
elements which have characteristics properties of both metals and non-metals, e.g.,
Germanium, Silicon, Tellurium, Antimony and Arsenic.
Question 5: Name any one metal which reacts neither with cold water nor
with hot water but reacts with heated steam to produce hydrogen gas.
Answer:
Question 6: Name two metals which are both ductile and malleable.
Answer: Gold and Silver.
Question 7: A green layer is gradually formed on a copper plate exposed
to air for a week in a bathroom. What is this green substance?
Answer: The green layer is
formed due to the formation of basic copper carbonate. [CuCO3.Cu
(OH)2].
CBSE Guide with additional CBSE Guess
questions - Class 10 Science, Metals and Non-Metals
Question 8: Why Tungsten metal is selected for making filaments of bulbs?
Answer: It is because Tungsten
has very high melting point and high resistivity.
Question 9: Name any two neutral oxides.
Answer: Nitrogen Monoxide (NO)
and Carbon Monoxide (CO).
Read: Class 10 Metals and Non-Metals: CBSE Notes, Important Definitions, Chemical Reactions and Equations
Question 10: Name the elements present in these alloys.
(i) Stainless Steel
(ii) Bronze
(iii) Brass
(iv) Duralumin
(v) German Silver
Answer:
(i) Stainless Steel =
Iron + Chromium + Nickel.
(ii) Bronze = Copper + Tin.
(iii) Brass = Copper + Zinc.
(iv) Duralumin =
Aluminium + Copper.
(v) German Silver =
Copper + Zinc + Nickel.
Question 11: Name the alloys which are used for the following purposes:
(i) For soldering joints.
(ii) For making windows and door-fittings.
(iii) For making aircrafts and kitchen-wares.
(iv) For making equipment for feed and dairy industry.
Answer:
(i) Solder,
(ii) Steel,
(iii) Duralumin,
(iv) Stainless Steel.
Question 12: Give reasons for the following:
(a) Metals are regarded as electropositive elements.
(b) Zirconium is known as a strategic metal.
(c) Reaction of nitric acid (HNO3) with metals generally does
not evolve hydrogen gas.
(d) Carbon is not used for making aluminium from aluminium oxide.
Answer: (a) Metals are regarded as electropositive elements
because it can loose electrons easily to form positive ions.
Answer: (b) Zirconium is a valuable
heavy mineral which is used in atomic power plants, nuclear reactor etc. Hence,
it is called a strategic metal.
Answer: (c) It is because nitric acid (HNO3) is a
good oxidising agent and so it oxidises H2 to H2O.
Answer: (d) Because aluminium is
stronger reducing agent than carbon and hence, carbon cannot be used for the
extraction of aluminium.
Question 13: Explain how the following metals are obtained from their
compound by the reduction process.
(a) metal, which is low in
reactivity series.
(b) metal, which is middle in the
reactivity series.
(c) metal, which is highly reactive.
Answer:
(a) Metals of low
reactivity series can be obtained by reduction using cake.
(b) Metal which are
intermediate in the reactivity series can be obtained by reduction using Al.
(c) Metal which are
highly reactive can be obtained by electrolytic reduction.
Question 14: How will you show that silver is less reactive than copper?
Answer: If we react copper with
silver nitrate solution then, copper will displace silver as per the following
chemical equation:
But silver cannot
displace copper from copper nitrate, hence, silver is less reactive than
copper.
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Guess Questions with Solutions |
Class 10 Science, Metals and Non-Metals
Question 15:
What is magnetic separation? Name two ores which are concentrated by using this
method?
Answer: Magnetic separation is a method of separating
magnetic ore from non-magnetic impurities using electromagnets. Name of the two
ores are:-
Pyrolusite (MnO2)
and Magnetite (Fe3O4).
Question 16: How will you show by an activity that copper is more
reactive than silver?
Answer: We take copper metal and add it to silver
nitrate solution. Leave it for 1 hour. After that we will observe that colour
of solution changes to blue and shiny silver metal gets deposited. This
activity shows that copper is more reactive than silver since, copper displaces
silver from silver nitrate solution. The reaction can be represented as -
Question 17: Define a chemical bond.
Answer: The attractive force
which holds together two atoms, two molecules, two ions or a combination of
these is known as a chemical bond.
Question 18: What is reactivity series of metals?
Answer: Reactivity or Activity
Series is a list of common metals which have been arranged in order of their
decreasing reactivity.
Question 19: What is metallic lustre?
Answer: Metals, in their pure state, have a shining
surface. This property is called as ‘metallic lustre’.
Question 20: We cannot group elements
according to their physical properties alone. Why? Or,
Why elements cannot be grouped according
to their physical properties alone?
Answer: Elements cannot be grouped according to their
physical properties alone, as there are many exceptions. For example -
1. All
metals except mercury exist as solids at room temperature.
2. Although
metals have high melting points, there are exceptions like - gallium and
caesium which have very low melting points.
3. Iodine
is a non-metal but it is lustrous.
4. Carbon
is a non-metal that can exist in many forms.
5. Metals are generally very hard or rigid but
alkali metals (lithium, sodium, potassium) are so soft that they can be cut
with a knife.
Question 21: Define with examples - 1. Allotrope, 2. Amphoteric Oxide,
3. Roasting
Answer:
1. Allotrope: Allotropes are the elements which exist in two or
more different forms in the same physical state. Allotropes generally differ in physical properties and may
also differ in chemical activity. Diamond, graphite and fullerenes are
three allotropes of
the element carbon.
2. Amphoteric Oxide: Metal oxides are
basic in nature. But some metal oxides show both basic and acidic natures such
as - aluminium oxide, zinc oxide, etc. Such metal oxides which react with both
acids and bases to produce salts and water are known as amphoteric oxides.
3. Roasting: It is a process in which the sulphide ores are
converted into oxides by heating strongly in presence of excess air. For
example,
Question 22: What is Inert Gas or Noble
Gas?
Answer: An inert gas or noble gas is a gas that has
extremely low reactivity with other substances. The noble gases for example - helium, argon, neon, xenon, krypton, radon,
and element 118 (Uuo) exist in
their elemental form. Noble or inert gases have a completely filled valance
sheel and hence, show little chemical activity.
Question 23: Most of the ores are found
in oxide form. Why?
Answer: Ores are found in the earth’s crust mainly as
oxides then as sulphides or carbonates. This is because oxygen is a very
reactive element and is very abundant on the earth.
Question 24: What is “Thermit Reaction”?
Answer: A Thermit Reaction is basically iron oxide (ferric
oxide) reacting with aluminum to produce molten iron. This is an exothermic
reaction. Iron obtained in this process is in molten state. Thermit reaction is
used for the welding of rails or cracked machine parts and the process is called
as Thermite welding.
Question 25: Name the most widely used
method for refining of metals?
Answer: The metals
produced by various ore reduction processes are not pure. They contain
impurities, which must be removed to obtain pure metals. The most widely used
method for refining of metals is Electrolytic Refining.
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