NCERT Class 6 Science Chapter 4 Sorting Materials into Groups Activity Solution
Activity 1 asks us to look around for nearby object and sort them by the material.
Objects: Material they are made of.
Pen: Plastic; Pencil: Wood; Book: Paper; Notebook: Paper; Newspaper: Paper; Geometry box: Steel; Bag: Nylon; Tiffin box: Plastic; Water bottle: plastic; Cloth: Cotton; Muffler: Wool; Chair: wood, Table: wood; Purse: leather; Handbag: Leather.
Activity 2 asks us to classify the objects found in activity 1 based on its material.
Material: Object made of these materials.
Wood: Pencil, Table, Chair.
Paper: Book, Notebook, Newspaper.
Leather: Purse, Handbag.
Plastics: Pen, Tiffin box, Water bottle.
Steel: Geometry box.
Activity 3 asks us to cut or rub various material and see if it shines or not.
Paper, Cardboard, wood, Chalk, tiffin box does not shine.
Aluminium sheet, Copper wire, glass tumbler shines.
Explanation: Metals and glass have lustrous property. They shine most of the time. They react with atmospheric air to form oxides. We call them rusting — such metals like aluminium and iron shine on rubbing.
Activity 4 asks us to check various objects whether they are soluble in water or not.
Salt, sugar, glucose, ORS, cold-drink, fruit juice are soluble in water.
While paper, book, chalk dust, sawdust, pen, pencil are not soluble in water.
The activity also asks about insoluble objects, whether they sink at the bottom or float on water. We will see this through activity 5.
Activity 5 asks us to check solubility of some common liquids in water.
Answer: Vinegar and lemon juice mix well with water while coconut oil, mustard oil and kerosene float on water.
Activity 6 asks us to check the transparency of paper using light. It also asks us to see the transparency of the paper after adding a few oil drops on it.
Some amount of light passes through the paper, but we can not see the object behind the paper.
After adding a few oil drops, paper become more transparent, and we can see some object present behind it.
Explanation: Adding a few drops of oil makes a paper more transparent. Such objects through which we can see across are called Translucent objects.