Class 6 Science Chapter 4 MCQ

We can group or identified any materials with the help of density. Generally, density possess some characteristics. As density is the amount of mass per unit of volume. If an object is heavy and compact, it has a high density. So, a simple example is if you have ever tried to mix water and oil. Oil is less dense than water, so it floats on top. A boat also floats for the same reason. And iron or stone are denser than water. Hence, they sink in water.

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.

Through magnifying glass and glass tumbler we can see the objects clearly so these materials are transparent.

Wood, glass and leather materials cannot be used for making safety pin. Steel and plastic are commonly used for making a safety pin.

Materials through which things cannot be seen are called “opaque” substances. Example wood, metals etc. Our palm and most of body parts are opaque. But when it (flesh, skin, cartilages, nerves) kept in powerful light source, it behaves like “translucent”. But still, the X-ray light source is not able to cross the bone of our body.

Water is known as Universal solvent. As it dissolves maximum materials. But oil, chalk, sawdust and sand are not dissolved in water.

Aluminum, iron and copper are the metals while Sulphur is non-metal.

The property of substances by which they can be beaten into thin sheets is called malleability. Bricks, pots and many other things is made by soil as a form of wet clay. Wet clay has the property of malleability and bricks are burned in a kiln which makes them durable.

Those substances through which things can be seen are called “transparent” substances. Example glass, water and air. Transparent material is used for making the front glass (windscreen) of a car.

Water is a conductor of electricity. Pure water is actually a good insulator. Tap water can be a good conductor due to calcium, magnesium, and carbonate ions, or other substances. Any impurities, like salts, in the water enable it to conduct electricity. Pure water does not conduct electricity. This is because pure water do not contain any salts or components.