NCERT Exemplar Problems Class 6 Science – Sorting Materials and Groups

Question 1:
An iron nail is kept in each of the following liquids. In which case would it lose its shine and appear dull?
(a) Mustard oil
(b) Soft drink
(c) Coconut oil
(d) Kerosene
Solution:
(b) An iron nail kept in soft drink would lose its shine and appear dull became soft drink contains carbonic acid which reacts with iron nail, so it gives dull appearance.
Iron nail has no reaction with mustard oil, coconut oil and kerosene, so does not lose its shine, when kept in these solutions.

Question 2:
Pick one material from the following which is completely soluble in water.
(a) Chalk powder
(b) Tea leaves
(c) Glucose
(d) Sawdust
Solution:
(c) Glucose is completely soluble in water because its particles are so small and spread uniformly in water that we cannot see them. But chalk powder, tea leaves and sawdust are insoluble in water and settle down at the bottom of the container.

Question 3:
You are provided with the following materials:

1. Magnifying glass
2. Mirror
3. Stainless steel plate
4. Glass tumbler

Which of the above materials will you identify as transparent?
(a) (1) and (2)
(b) (1) and (3)
(c) (1) and (4)
(d) (3) and (4)
Solution:
(c) Through magnifying glass and glass tumbler we can see the objects clearly so these materials are transparent.

Question 4:
Boojho found a bag containing the following materials:

1. Mirror
2. Paper stained with oil
3. Magnet
4. Glass spectacles

Help Boojho in finding out the material(s) which is/are opaque.
(a) Only (1)
(b) Only (4)
(c) (1) and (3)
(d) (1) and (4)
Solution:
(c) Mirror and magnet are opaque materials because we cannot see through these materials. Paper stained with oil is translucent material and glass spectacles is transparent.

Question 5:
While doing an activity in class, the teacher asked Paheli to handover a translucent material. Which among the following materials will Paheli pick and give her teacher?
(a) Glass tumbler
(b) Mirror
(c) Muslin cloth
(d) Aluminium foil
Solution:
(c) The material through which an object can be seen but not clearly is called translucent.
Hence, muslin cloth is a translucent material. Mirror and aluminium foil are opaque and glass tumbler is transparent material.




Question 6:
Which pair of substances among the following would float in a tumbler half-filled with water?
(a) Cotton thread, thermocol
(b) Feather, plastic ball
(c) Pin, oil drops
(d) Rubber band, coin
Solution:
(b) All the materials, which are lighter than water, float on water here feather and plastic ball. Among the given pair of substances which would float in a tumbler half-filled with water.

Question 7:
Which among the following are commonly used for making a safety pin?
(a) Wood and glass
(b) Plastic and glass
(c) Leather and plastic
(d) Steel and plastic
Solution:
(d) Wood, glass and leather materials cannot be used for making safety pin. Steel and plastic are commonly used for making a safety pin.

Question 8:
Which of the following materials is not lustrous?
(a) Gold
(b) Silver
(c) Wood
(d) Diamond
Solution:
(c) Gold, silver and diamond have shiny appearance are said to have luster. Wood has dull appearance, so wood is not lustrous.

Question 9:
Which of the following statements is not true?
(a) Materials are grouped for convenience
(b) Materials are grouped to study their properties
(c) Materials are grouped for fun
(d) Materials are grouped according to their uses
Solution:
(c) Materials are grouped for our convenience and to make it convenient to study their properties. Materials are also grouped according to their uses.

Question 10:
Find the odd one out from the following.
(a) Tawa
(b) Spade
(c) Pressure cooker
(d) Eraser
Solution:
(d) Tawa, spade and pressure cooker are all hard materials i.e. cannot be easily compressed, cut, bent (moulded) or scratched but eraser can be easily cut, bent or scratched. So, the odd one is eraser.

Question 11:
Which type of the following materials is used for making the front glass (wind screen) of a car?
(a) Transparent
(b) Translucent
(c) Opaque
(d) All of these
Solution:
(a) Transparent material is used for making the front glass (wind screen) of a car.

Very Short Answer Type Questions

Question 12:
It was Paheli’s birthday. Her grandmother gave her two gifts made up of metals, one old dull silver spoon and a pair of lustrous gold ear-rings. She was surprised to see the difference in the appearance of the two metals. Can you explain the reason for this difference?
Solution:
Gold metal does not lose its shine or luster when exposed to atmosphere. So gold ornaments look new even after several years of use. Actually, gold metal is highly unreactive metal which remains unaffected by air, water and other gases in the atmosphere whereas silver metal on long exposure to moist air loses its shine and becomes dull. That why old silver spoon was giving dull appearance.

Question 13:
Mixtures of red chilli powder in water, butter in water, petrol in water and honey in water were given to Radha, Sudha, Sofia and Raveena, respectively. Whose mixture is in solution form?
Solution:
Raveena has got a solution because honey will dissolve in water whereas red chilli powder, butter and petrol float on water.

Question 14:
On a bright sunny day, Shikha was playing hide and seek with her brother. She hid herself behind a glass door. Do you think her brother will be able to locate her? If yes, why? If no, why not?
Solution:
Yes, her brother can easily locate her because glass door is a transparent material. The transparent materials allow almost all the light to pass through them due to which the object or person behind them can be seen clearly.

Question 15:
Take a small cotton boll and place It in a tumbler/bowl filled with water.
Observe it for at least 10 minutes. Will it float or sink in water and why?
Solution:
Cotton boll initially floats on water but after few minutes (i.e. 10 min), it sinks because it absorbs water.

Short Answer Type Questions

Question 16:
Which among the following materials would you identify as soft materials and why?
Ice, rubber band, leaf, eraser, pencil, pearl, a piece of wooden board, cooked rice, pulses and fresh chapatti.
Solution:
Materials which can be compressed, cut, bent (moulded) or scratched easily are called soft materials.Rubber band, leaf, eraser, cooked rice and fresh chapati are soft materials because they can be compressed, cut, bent or scratched easily.

Question 17:
You are provided with the following materials: Turmeric, honey, mustard oil, water, glucose, rice flour, groundnut oil.
Make any three pairs of substances where one substance is soluble in the other and any three pairs of substances where one substance remains insoluble in the other substance.
Solution:
Substances which are soluble :
(i) Honey in water
(ii) Glucose in water
(iii) Groundnut oil in mustard oil Substances which are insoluble :
(i) Turmeric in water
(ii) Rice flour in water
(iii) Mustard oil in water

Question 18:
During summer holidays, a group of children collected a lump of salt, green grass, broken glass piece, a small thermocol box, pen, iron nail, glass marbles, hair, naphthalene ball, a piece of sugar candy (mishri) and tried to group them on the basis of properties given in table. Help them in filling the table.

Solution:
The complete table is shown as below :

Question 19:
Arrange the jumbled words to arrive at the appropriate names of materials and also write two uses of each.
(a) Milaunuim
(b) Tcaslpi
(c) Soekrnee
(d) Gavnier
Solution:
Arrangement of the words and their uses are as follows:
(a) Aluminium It is used in foil, aircrafts, etc.
(b) Plastic It is used in making bucket, pencil box, etc.
(c) Kerosene It is used as a fuel, solvent, etc.
(d) Vinegar It is used in food ingredient, preservative, etc

Question 20:
Match the objects given in Column I with the materials given in Column II.

Solution:
The correct matching is as given:
(a)—(iii), (b)—(iv), (c)—(i), (d)–(ii)
Note: (a) Surgical instruments are made up of steel.
(b) Newspaper is made up of paper and paper is obtained from plants.
(c) Electrical switches are made up of plastic.
(d) Wool is obtained from wool yielding animals so wool is animal product.




Question 21:
Crossword Puzzle Pick five objects from the word box given as figure, which are opaque and would sink in water.

Solution:
Name of the objects, which are opaque and would sink in water are :

1. Coal
2. Stone
3. Pencil
4. Eraser
5. Coin

Long Answer Type Questions

Question 22:
Chalk, iron nail, wood, aluminium, candle, cotton usually look different from each other. Give some properties by which we can prove that these materials are different.
Solution:
We can differentiate these materials on the basis of lustre, hardness, softness, roughness or smoothness.

Question 23:
Why do you think oxygen dissolved in water is important for the survival of aquatic animals and plants.
Solution:
Oxygen gas dissolves in water i.e. oxygen gas is soluble in water. The plants and animals which live in water use the oxygen dissolved in water for respiration. Thus, oxygen gas dissolved in water is very important for the survival of animals and plants that live in water.

Question 24:
Differentiate among opaque, translucent and transparent materials, giving one example of each.
Solution:
Opaque Those materials through which we cannot see at all are called opaque materials, e.g. Car board.
Translucent Those materials through which we cannot see clearly are called translucent materials, e.g. Butter paper.
Transparent Those materials through which we can see clearly are called transparent materials e.g. Glass.

Question 25:
Sugar, salt, mustard oil, sand, sawdust, honey, chalk powder, petals of flower, soil, copper sulphate crystals, glucose, wheat flour are some substances given to Paheli. She wants to know whether these substances are soluble in water or not. Help her in identifying soluble and insoluble substances in water.
Solution:
Substances which completely dissolve in water are soluble in water.
Substances soluble in water are sugar, salt, honey, copper sulphate crystals, glucose.
Substances which does not dissolve in water are insoluble in water. Substances insoluble in water are mustard oil, sand, sawdust, chalk powder, petals of flower, soil, wheat flour.