Samacheer Kalvi Class 8 Science Unit 9 Matter Around Us Solutions
Welcome to NCTB Solutions. Here with this post we are going to help 8th class students by providing Solutions for Samacheer Kalvi Class 8 Science Unit 9 Matter Around Us. Here students can easily find all the solved solution for Matter Around Us Exercise questions. Also here our Expert Science Teacher’s solved all the questions with easily understandable language with proper guidance so that all the students can understand easily. Here on this post students will get Unit 9 Matter Around Us exercise solutions. Here all the solutions are based on Tamil Nadu State Board latest syllabus.
Unit 9 Matter Around Us Exercise Questions Solutions :
(I) Choose the best answer
(1) The liquid metal used in thermometers is
(a) copper
(b) mercury
(c) silver
(d) gold
Answer :
Correct Option → (b)
Mercury is used in thermometers because they are found in liquid state even in room temperature.
(3) Which one of the following elements name is not derived from planet
(a) Plutonium
(b) Neptunium
(c) Uranium
(d) Mercury
Answer :
Correct Option → (d)
Mercury is not derived from planet.
(4) Symbol of mercury is
(a) Ag
(b) Hg
(c) Au
(d) Pb
Answer :
Correct Option → (b)
Symbol of mercury is Hg
(5) A form of non-metal which has high ductility is
(a) nitrogen
(b) oxygen
(c) chlorine
(d) carbon
Answer :
Correct Option → (d)
A form of non-metal which has high ductility is Carbon.
(6) The property which allows the metals to be hammered into their sheets is __
(a) Ductility
(b) Malleability
(c) Conductivity
(d) Shining strength
Answer :
Correct Option → (b)
The property which allows the metals to be hammered into their sheets is Malleability.
(7) The non-metal which conducts electric current is
(a) Carbon
(b) Oxygen
(c) Aluminium
(d) Sulphur
Answer :
Correct Option → (a)
The non-metal which conducts electric current is Carbon.
(9) Pencil lead contains ___.
(a) Graphite
(b) Diamond
(c) Aluminium
(d) Sulphur
Answer :
Correct Option → (a)
Pencil lead contains Graphite.
(II) Fill in the blanks
(1) The element which possesses the character of both metals and non metals are called ____
(2) The symbol of tungsten is ____
(3) Melting point of most metal is ____ than non-metal.
(4) Water contains ____ and ____ element.
(5) ____ is used as semiconductor.
Answer :
(1) → Metalloids
(2) → W
(3) → High
(4) → Hydrogen and Oxygen
(5) → Germanium
(III) Match the following
| Column A (Substance) | Column B (Application) |
| (a) oxygen | (i) for making crackers |
| (b) copper | (ii) for disinfecting water |
| (c) sulphur | (iii) all living beings inhale during breathing |
| (d) iron | (iv) for making electric wires |
| (e) chlorine | (v) for making rails |
Answer :
(a) Oxygen → (iii) all living beings inhale during breathing.
(b) Copper → (iv) for making electric wires.
(c) Sulphur → (i) for making crackers.
(d) Iron → (v) for making rails.
(e) Chlorine → (ii) for disinfecting water.
(IV) Answer very briefly
(1) What is ductility?
Answer :
Metals can be drawn into thin wires this property of metals are known as ductility. For e g – copper wires.
(3) Write the symbols for the following elements.
(a) Oxygen
(b) Gold
(c) Calcium
(d) Cadmium
(e) Iron
Answer :
(a) Oxygen → O
(b) Gold → Au
(c) Calcium → Ca
(d) Cadmium → Cd
(e) Iron → Fe
(4) Which non-metal is essential for our life and all living beings?
Answer :
The Non-metals like hydrogen, nitrogen, carbon, diamond, graphite, chlorine, oxygen sulphur and phosphours are some non-metals which we used in our daily life.
(5) Why are bells made of metals?
Answer :
Bells are made of metals because on bring hit metals are produced a typical sound therefore they are said as sonorous and used for making bells.
(6) What does a chemical symbol represent?
Answer :
Chemical symbol represent of elements because the in chemistry there are various elements which have different name and every time writing a name of element is slightly too troublesome therefore the name of an element is represented by shortened for which is known as symbol.
(7) Give two examples for metalloids.
Answer :
Examples for metalloids are Boron, Silicon and Germanium
(8) Mention any three compounds that exist in liquid state.
Answer :
Three compounds that exist in liquid state are Water, Hydrochloric acid, Sulfuric acid etc.
(9) Write three properties of metalloids.
Answer :
Three properties of metalloids are as follows :-
(A) Metalloids are solids at room temperature
(B) They can form alloys with other metals
(C) Some metalloids such as silicon and germanium acts as electrical conductors under specific condition.
(V) Answer briefly
(1) Can you store pickle in an aluminium utensil? Give reason.
Answer :
No, we cannot store lemon pickle in aluminium utensil.
Lemon is a citrus fruit which means they contain acid, and Aluminium is a metal. If we keep lemon pickle in aluminium utensil the acid present in lemon pickle will react with aluminium and form toxic salts which can cause damaging effect to our health.
(2) Tabulate the differences between metals and non-metals.
Answer :
- Metals :
(1) Metals are usually solid at room temperature .
(2) They shows malleability property.
(3) Melting and boiling point is high
(4) They are good conductor of electricity
- Non metals :
(1) Non-metals are solids, liquid or gas at room temperature.
(2) They are usually soft pr brittle.
(3) Melting and boiling point is low
(4) They are bad conductor of electricity.
(3) Why are utensils made up of aluminium and brass?
Answer :
The utensils are made up of aluminum and brasses because metals are the good conductor of heat and when utensils are made from metals they heat fastly and cook food also fast therefore utensils are made from aluminum and brass.
(4) Define Alchemy
Answer :
The used of different material from people or man and represented in the different symbol and tried to change less valuable metal into gold this process is known as Alchemy.
(6) Name six common non-metals and write their symbols.
Answer :
Six common non-metals and their symbols are as follows
Oxygen – O
Carbon – C
Sulphur – S
Chlorine – Cl
Hydrogen – H
Phosphorous – P
(7) Mention any four compounds and their uses.
Answer :
Four compounds and their uses are as mention below :-
(a) Water → for drinking and as solvent
(b) Table salt → essential component of our daily diet, preservative for meat and fish
(c) Lime soda → preparation of chalk powder
(d) Washing soda → as cleaning agent.
(8) Name the metals that are used in jewellery.
Answer :
Silver and gold are used to make jewellery.
(9) Mention the uses of the following compounds.
(a) Baking soda
(b) Bleaching powder
(c) Quick lime
Answer :
(a) Banking soda : Fire extinguisher, preparation of baking powder and preparation of cakes and bread
(b) Bleaching powder : As bleaching agent, disinfectant and sterilization of drinking water.
(c) Quick lime : Manufacture of cement.
(VI) Given reason
(1) Give reasons for the following
(a) Aluminum foils are used to wrap food items.
Answer :
Reason : Aluminum are metal and show the malleability and forms sheet easily and also conduct heat and make food hot therefore aluminum foils are used to wrap food items.
(b) Immersion rods for heating liquids are made up of metallic substances.
Answer :
Reason : Metals are good conductor of heat so how to make immersion rods for heating liquids are made of metallic substances.
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