Kerala Syllabus Class 6 Basic Science: Chapter 05 Association of Substances - Questions and Answers | Teaching Manual
ഈ ബ്ലോഗ് അഡ്മിൻറെ രേഖാമൂലമുള്ള അനുമതിയില്ലാതെ ഈ ബ്ലോഗിൽ നൽകിയിരിക്കുന്ന ചോദ്യോത്തരങ്ങൾ, ഇതേരീതിയിലോ പി.ഡി.എഫ് രൂപത്തിലോ, മറ്റേതെങ്കിലും ഡിജിറ്റലോ, പ്രിന്റഡ് ഉൾപ്പെടെയുള്ള ഏതെങ്കിലും രൂപങ്ങളിലേക്കോ മാറ്റി മറ്റൊരു വെബ്സൈറ്റിലോ, ബ്ലോഗിലോ, യുട്യൂബ്, സോഷ്യൽ മീഡിയാ ഗ്രൂപ്പുകളിലോ ഉൾപ്പെടെ ഒരിടത്തും പ്രചരിപ്പിക്കാൻ പാടില്ലാത്തതാകുന്നു.
Std 6: Basic Science Chapter 05: Association of Substances - Questions and Answers
♦ You might have guessed what the boy is talking about. What are the different items in this snack? Examine the snack and find out the items in it.
• Groundnut
• Fried gram
• Curry leaves
• Salt
• Chilly powder
• Sev or noodles
• Boondi
♦ Which are the substances used to make concrete?
• Cement
• Sand
• Metal (Gravel)
• Water
♦ What are the peculiarities of concrete, compost and mixture?
They are made by mixing more than one substance.
♦ Which are the ingredients usually used in salad and mango pickle?
• Salad - Onion, Tomato, Cucumber, Carrot, green chilly, curd, salt
• Mango pickle - Mango, green chilli, garlic, mustard, fenugreek, chilly powder, turmeric powder, vinegar, salt
♦ What are mixtures?
A mixture is a combination of more than one substance.
♦ Take the following materials from the Science Kit. How many mixtures can be made from them?
Materials required: Water, salt, sugar, chalk powder, lemon, blue vitriol, potassium permanganate, iron powder, rava, green gram, bengal gram, paddy, transparent vessels, glass tumblers, small vessels and spoons
| Mixture prepared | Components |
|---|---|
| Lime juice | Lemon juice + Sugar + Salt + Water |
| Potassium permanganate Solution | Potassium permanganate + Water |
| Paddy - Rava mixture | Paddy + Rava |
| Iron powder - salt mixture | Iron powder + salt |
| Bengal gram - Green gram mixture | Bengal gram + Green gram |
| ORS Solution | Sugar + Salt + Water |
| Chalk powder - Water mixture | Chalk powder + Water |
♦ Do all the ingredients in the mixtures you have prepared belong to the
same state of matter?
No, some mixtures are of the same state, some are not.
♦ Which are the mixtures in which a solid is dissolved in a liquid?
Lime juice, Potassium permanganate Solution, ORS Solution, Blue vitriol solution
Salt solution
♦ Are there any mixtures of two solids?
Yes
♦ Which are the mixtures with more than one solid dissolved in a liquid?
ORS Solution, Blue vitriol potassium permanganate Solution
♦ Mixtures with solid dissolved in liquid
• Salt water
• Sugar solution
• ORS Solution,
• Blue vitriol Solution,
• Potassium permanganate Solution
♦ Mixtures of solids
• Rava mixed with salt
• Paddy - Rava mixture
• Iron powder - salt mixture
• Bengal gram - Green gram mixture
♦ Mixtures with more than one solid dissolved in liquid
• Potassium permanganate and salt dissolved in water
• ORS Solution
• Blue vitriol potassium permanganate Solution
♦ Mixtures in which all components are visible.
• Chalk powder in water
• Paddy - Rava mixture
• Iron powder - salt mixture
• Bengal gram - Green gram mixture
♦ Mixtures in which all components are not visible.
• Salt solution
• Lime juice
• Potassium permanganate Solution
• Sugar solution
• ORS Solution,
• Blue vitriol Solution
♦ What is solution?
A solution is formed by dissolving a solute in a solvent.
♦ What is solute?
A substance that dissolves is called a solute
♦ What is solvent?
The substance in which the solute dissolves is called a solvent.
♦ You know that solutions are formed by dissolving a solute in a solvent. Find more examples for solutions. Tabulate them.
♦ Name the solutions formed by dissolving solid in another solid.
916 gold, brass, bronze
♦ Name a solid-gas solution.
The solution of palladium and hydrogen gas
♦ Take equal quantities of water in glasses of same size. Prepare the following and observe.
• Mixture 1. Water with sugar dissolved in it.
• Mixture 2. Salt solution
• Mixture 3. Water mixed with chalk powder
Examine the mixtures you have prepared
♦ Are these mixtures alike?
No
♦ What are the similarities between sugar solution and salt solution?
Both are clear solutions. Sugar and salt dissolve completely in water. The particles will not settle at the bottom after some time.
♦ What is the difference between water mixed with chalk powder and salt solution?
In salt solution, salt dissolves completely, but in water mixed with chalk powder, chalk powder does not dissolve completely. The chalk powder settles at the bottom after some time, but in salt solution, salt never settles down.
♦ Take the sugar solution you have prepared earlier. Take the same amount of water and sugar in a similar glass and keep it unstirred. Using a straw, carefully taste from different parts of the water with dissolved sugar and the unstirred mixture of sugar and water. Record the differences in taste in the table below.
♦ Is the sweetness the same everywhere in the well-stirred sugar solution?
Yes, the sweetness is same everywhere.
♦ What about the taste of the solution taken from different parts of the unstirred sugar solution?
The sweetness varies in different parts of the unstirred sugar solution
♦ Aren’t the components the same in both? Yet what could be the reason for the difference in taste?
• Both mixtures contain the same components.
• In the well-stirred solution, the sweetness is uniform throughout because the sugar has completely dissolved and spread evenly in the water.
• In the unstirred solution, the distribution of sugar at different parts varies. The sugar remains mostly at the bottom.
♦ Homogeneous Mixtures and Heterogeneous Mixtures
The mixture that shows the same properties throughout all its parts is called a homogeneous mixture. The mixture that shows different properties in different parts is called Heterogeneous mixture.
♦ Are the mixtures with dissolved salt and that with undissolved salt the same? How are they different?
No, the mixture with dissolved salt is homogeneous, and the mixture with undissolved salt is heterogeneous
♦ Is the mixture of chalk powder and water homogeneous or heterogeneous? Why?
Heterogeneous, the chalk powder is not uniformly mixed.
♦ Are compost, concrete mix and the edible mixture homogeneous or heterogeneous? Why?
• Heterogeneous
• The components in the compost, concrete mix and the edible mixture are not uniformly distributed everywhere. They show different properties at different parts.
♦ Classify the mixtures you have prepared so far into homogeneous mixtures and heterogeneous mixtures and write them in the table below.
| Homogeneous mixtures | Heterogeneous mixtures |
|---|---|
| Lime juice | Chalk powder solution |
| Potassium permanganate Solution | Bengal gram Green gram mixture |
| Sugar solution | Paddy Rava mixture |
| Vinegar | Iron powder salt mixture |
| Air | Concrete |
| Steel, Brass, 916 gold | Compost |
| Soft drinks | Salad |
| ORS Solution | Muddy water |
| Alcohol water solution | Vegetable soup |
| Sea water | Pickles |
♦ What are the components in the air? Compare their quantities.
| Gas | Quantity |
|---|---|
| Nitrogen | 78% |
| Carbon dioxide | 0.04% |
| Oxygen | 21% |
| Others | 0.96% |
♦ Put the gravel in a plastic jar and shake it well. Using a marker pen, mark the level of gravel on the outer surface of the jar. Add some green gram to this and stir the jar. Does the level of gravel rise now? Write the measurement in the table. Then put some Rava in the plastic jar and shake it well. Does the height of the gravel change after this? Record the observation in the table below.
| Activity | Height of gravel in the jar |
|---|---|
| After shaking and pressing the gravel in the jar | 10 cm |
| After adding the green gram in the jar and shaking it | 10 cm |
| After adding the rava in the jar and shaking it well | 10 cm |
Analyse the table below.
• Does the level of the gravel inside the jar change after adding green gram and rava and shaking them down? Why?
No, the level remains constant.
When green gram and rava are added and shaken, they settle into the spaces between the gravel pieces.
• Where have the green grams settled?
Green grams settle between the gravel pieces.
• Where have the rava grains settled?
Rava grains settle in the tiniest spaces between the gravel and green gram.
• When rava and green gram are added to the gravel in the jar and shaken, was there any difference in the total space required for all the three?
No
• How can green gram stay along with gravel and rava grains settle in between the two?
Green gram settles into the larger gaps between gravel pieces, while rava grains fill the tiny spaces between both, allowing all three to fit together without needing extra space.
These grains are smaller than the empty space between the gravel pieces.
♦ What is a molecule?
Molecule is the smallest particle of a substance having all its properties. All substances are made up of molecules.
♦ Check the illustration given below to know how the molecules are arranged in solids, liquids and gases around us. Find out how the molecules exist in each state.
Solid
• In which state of matter are the molecules the farthest?
Gas
• Why do solids have a definite shape while gases and liquids don't have?
In solid, the molecules are very close to each other. The attractive force between the molecules is higher. Solids have a definite shape because their molecules are tightly packed and arranged in a fixed pattern.
The molecules in liquids and gases move freely. liquids flow and take the shape of their container, while gases spread out to fill all available space.
♦ A mixture is a combination of more than one substance. So wouldn’t there be more than one type of molecule in a mixture? Note the illustration showing the molecules in different substances.
Only one kind of molecule
• What about B?
Two kinds of molecules
• Which substances have different types of molecules?
mixtures are made up of different types of substances
• Which substances have the same type of molecules?
Some substances are made up of same type of molecules. These are pure substances.
• Which are the mixtures in the picture?
B and C
• From the above illustrations of substances A, B, C and D, identify pure substances and mixtures.
A and D are pure substances
B and C are mixtures
♦ What are Pure Substances?
Pure substances are substances made up of same type of molecules.
♦ Are mixtures pure substances? Why?
No, Mixtures are composed of different types of molecules.
♦ Water without any impurities is a pure substance. Why?
Water without any impurities is a pure substance because it contains only one type of molecule—H₂O
♦ Classify the following substances as pure substances and mixtures and complete the table appropiately.
| Substance | Molecules involved | Pure substance/ Mixture |
|---|---|---|
| Porridge | Water, salt and other substances | mixture |
| Pencil graphite | Graphite | Pure substance |
| Sugar | Sugar | Pure substance |
| Soda water | Carbon dioxide, water | mixture |
| Buttermilk | Water, salt and other substances | mixture |
| Pure water | Water | Pure substance |
| Potassium permanganate | Potassium permanganate | Pure substance |
| Gold jewels | Gold, silver and copper | mixture |
| Gold | Gold | Pure substance |
♦ Find more examples for each category and complete the table.
• Oxygen
• Gold
• Iron
• Water
• Sodium chloride
• Carbon dioxide
2. Homogeneous mixture
• Saltsolution
• Vinegar
• Air
• Brass
• Sugar solution
3. Heterogeneous mixture
• Salad
• Sand and iron filings
• Oil and water
• Cereal in milk
♦
Rice, stone, sand and iron powder
• Do rice and stone have same colour? Do they have same shape and size?
No, rice and stone have different colour, shape and size.
• The components of which of these mixtures can be seperated by hand?
Rice mixed with stones
• If the stones have the same size and colour that of rice, would it be possible to seperate them by hand?
No
• Can iron powder be separated from sand by making use of any other property of iron powder?
Yes, iron powder can be separated from sand using a magnet. Iron is magnetic, and sand is not.
♦ Find out more instances of separating components in the same way and list them in the table below.
| Separation by Picking Up | Separation Using Magnet |
|---|---|
| • Stones from rice or pulses | • Iron filings from sand |
| • Leaves from dry grass | • Iron pins from sawdust |
| • Large pieces of plastic from soil | • Iron nails from a mixture of nails and plastic |
| • Broken glass pieces from sand | • Iron powder from salt |
♦ Discuss the different types of separation used in the following situations. Examine the properties of the components utilized in each situation.
• How do we separate tea dust from tea?
By filtration using a strainer.
• How are small stones removed from rice while washing it before cooking?
While washing rice before cooking, the denser stones sink to the bottom of the bowl.
• Which are the ways by which muddy water can be purified?
Muddy water can be purified by filtration and sedimentation to remove soil and dirt particles.
• How are gravel and other waste materials separated from the sand used for construction works?
By sieving
♦ Observe the pictures.
| Situations | Method of separation |
|---|---|
| • Salt is separated from seawater collected in salt fileds | • Evaporation |
| • Butter is separated from curd. | • Centrifugation |
| • Iron powder is separated from sand | • Magnetic separation |
| • Paddy and chaff are separated | • Winnowing |
• From the table, identify the context that utilises the change of state of matter for the separation of dissolved component.
Separating salt from seawater collected in the salt field
• How is the process of separating butter from curd different from others?
When the curd is whirled, due to the strong rotational force, the lighter butterfat particles are separated from the curd.
• Which situation makes use of the magnetic property of the component for separation?
Separating iron powder from sand
• Which property is used to separate chaff from paddy?
By using the differences in the weight of paddy and chaff
Let’s Assess
1. A drink is prepared by mixing, salt and sugar to soda water.
a) What are the components of this mixture?
Water, carbon dioxide, salt, sugar
b) Is this drink a homogeneous or heterogeneous mixture?
Homogeneous mixture
2. One spoon of salt is added to a glass of water. There is undissolved salt in the glass. What should be done to make it a homogeneous mixture?
Stir the mixture thoroughly.
3. Examine the following statements about iron, brass, gold ornament, bronze, carbon dioxide and aluminium. Tick (✔) the correct ones among these.
a) All these are not pure substances. (✔)
b) Brass, Iron and bronze are metallic mixtures.
c) Gold ornament is a mixture. (✔)
d) Carbon dioxide and aluminium are pure substances. (✔)
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