NCERT Solutions: Sorting Materials into Groups

The things, which we all use in our daily life are made up of different types of materials. All these materials have mass, shape and are classified based on many criteria, including their physical states, properties of materials, etc.

Let's have a look at the questions and answers for a better understanding.

Exercises

Q1. Name five objects which can be made from wood.
Ans: Table, Chair, Bed, Desk, Bullock cart.

Q2. Select those objects from the following which shine: Glass bowl, plastic toy, steel spoon, cotton shirt
Ans: Glass bowl and steel spoon.
Explanation: Glass and steel have smooth, reflective surfaces that send back light, so they appear shiny. Plastic toys and cotton shirts have duller surfaces and do not reflect light in the same way.

Glass bowl

Steel Spoon

Q3. Match the objects given below with the materials from which they could be made. Remember, an object could be made from more than one material and a given material could be used for making many objects

Ans:

Q4. State whether the statements given below are True or False.
(i) Stone is transparent, while glass is opaque.
Ans: False
Explanation: Stone is generally opaque and does not let light pass through. Glass is usually transparent and allows light to pass through.

(ii) A notebook has lustre while an eraser does not.
Ans: False
Explanation: A notebook is made of paper and has a dull surface, so it does not show lustre. An eraser also normally has a dull, non-shiny surface.

(iii) Chalk dissolves in water.
Ans: False
Explanation: Chalk is insoluble in water. It breaks into small particles when mixed with water and settles down rather than dissolving.

(iv) A piece of wood floats on water.
Ans: True
Explanation: Many types of wood are less dense than water, so a piece of wood floats on water.

(v) Sugar does not dissolve in water.
Ans: False
Explanation: Sugar is soluble in water and dissolves readily to form a uniform solution.

(vi) Oil mixes with water.
Ans: False
Explanation: Oil and water do not mix; oil is less dense and forms a separate layer above water.

(vii) Sand settles down in water.
Ans: True
Explanation: Sand is insoluble in water and, being denser than water, sinks and settles at the bottom.

(viii) Vinegar dissolves in water.
Ans: True
Explanation: Vinegar (a dilute solution of acetic acid) is soluble in water and mixes completely to form a uniform mixture.

Q5. Given below are the names of some objects and materials: Water, basketball, orange, sugar, globe, apple and earthen pitcher Group them as:
(a) Round shaped and other shapes
Ans: Round shaped: Basketball, orange, globe, apple and earthen pitcher.
Other shapes: Water (takes the shape of its container) and sugar (granules).

(b) Eatables and non-eatables
Ans: Eatables: Water, orange, sugar and apple.
Non-eatables: Basketball, globe and earthen pitcher.

Q6. List all items known to you that float on water. Check and see if they will float on an oil or kerosene.
Ans: Here is a list of common items that float on water and a note on whether they float on oil or kerosene:

• Paper - Floats on water, and also floats on oil and kerosene because it traps air and is light.
• Plastic - Some objects float and some sink depending on the material and the liquid.
• Thermocol (Styrofoam) - Floats on water, oil and kerosene because it is very light and contains air pockets.
• Wax - Floats on water and oil, but sinks in kerosene.
• Balloon - When filled with air, it floats on water, oil and kerosene as an object because it is filled with air and is light.

Other things that can float on water:

• Ice, wood, sponge, some ships and large pieces of polystyrene.

Note: Whether an object floats on oil or kerosene depends on the densities involved. Some items float on water but may sink in kerosene if they are denser than kerosene.

Q7. Find the odd one out from the following:

(a) Chair, Bed, Table, Baby, Cupboard
Ans: Baby: The rest (Chair, Bed, Table, Cupboard) are non-living objects usually made of wood or other materials; baby is a living being.

(b) Rose, Jasmine, Boat, Marigold, Lotus
Ans: Boat: The rest (Rose, Jasmine, Marigold, Lotus) are flowers; a boat is not a flower.

(c) Aluminium, Iron, Copper, Silver, Sand
Ans: Sand: Aluminium, Iron, Copper and Silver are metals; sand is not a metal.

(d) Sugar, Salt, Sand, Copper sulfate
Ans: Sand: Sugar, salt and copper sulfate form crystalline solids; sand is made of small rock particles and is not crystalline in the same way.