Class 8 Science Chapter 4 MCQ

Color of the copper metal is not responsible for copper to be used as electrical conduction wires.

Sodium metal is very reactive. It reacts vigorously with oxygen and water. A lot of heat is generated in the reaction. It is, therefore, stored in kerosene.

The product formed in the reaction of sulphur and oxygen is sulphur dioxide gas. When Sulphur dioxide is dissolved in water sulphurous acid is formed. The sulphurous acid turns blue litmus paper red. Generally, oxides of non-metals are acidic in nature.

When sulphur burns in air creates “Sulphur dioxide gas”. Please note that when we want to react a metal with oxygen, we usually burn the metal in air. It is the oxygen present in air which combines with the metal on burning to form a metal oxide.

During the rusting of iron or iron metal combines slowly with the oxygen of air in the presence of water moisture to form a compound called “iron oxide”. This iron oxide is rust the reaction of iron metal with oxygen in the presence of water. Therefore, oxide of iron rust is corrosion, it is a “Chemical reaction”.

Aluminum reacts with hydrochloric acid as well as sodium hydroxide solution to produce hydrogen gas.

During the rusting of iron or iron metal combines slowly with the oxygen of air in the presence of water moisture to form a compound called “iron oxide”. This iron oxide is rust the reaction of iron metal with oxygen in the presence of water. Therefore, oxide of iron rust is corrosion, it is a “Chemical reaction”.

When magnesium burns in air it combines with oxygen of air to form magnesium oxide (which is a basic oxide). Magnesium oxide dissolves in water to form magnesium hydroxide solution. Magnesium hydroxide turns red litmus. It is a base and that magnesium oxide is a basic oxide.

When magnesium burns in air it combines with oxygen of air to form magnesium oxide (which is a basic oxide). Magnesium oxide dissolves in water to form magnesium hydroxide solution. Magnesium hydroxide turns red litmus. It is a base and that magnesium oxide is a basic oxide.

The less reactive metals like copper, silver and gold do not react with dilute hydrochloric acid to produce hydrogen gas.

Here, all the statements are correct. Hence your answer will be option [D].

Mercury is the only metal which is found in liquid state at room temperature.

Metals are generally hard. This means that most of the metals cannot be cut easily. But sodium metal is soft and can be easily cut with a knife.

Non-metals can be cut easily. Non-metals have usually low melting point and low boiling points. Here, only option [A] is correct, as solid non-metals are usually neither hard not strong.

Here, all the above statements are correct. Hence, your answer will be option [D].

Metals have high melting points and high boiling points. Rest of all are correct.

Piece of coal is a non-metal which broke into small pieces when hammered.

A substance which cannot be broken down into two or more simpler substances by chemical reaction by applying heat, by light or by electricity, is called an element. Therefore, here option [A] is incorrect.

The property which allows the metals to be hammered into thin sheets is called malleability. Malleability is an important characteristic property of metals. Remember, malleable means which can be beaten (without broken down) by a hammer to form thin sheets.

Metals can be beaten into thin sheets with a hammer. Non-metals break into small pieces when hammered. So, zinc granule will be flattened on beating with a hammer.

Copper, aluminum and iron are metals but sulphur is not a metal.

When magnesium burns in air it combines with oxygen of air to form magnesium oxide (which is a basic oxide). Magnesium oxide dissolves in water to form magnesium hydroxide solution. Magnesium hydroxide turns red litmus. It is a base and that magnesium oxide is a basic oxide.

The product formed in the reaction of sulphur and oxygen is sulphur dioxide gas. When Sulphur dioxide is dissolved in water sulphurous acid is formed. The sulphurous acid turns blue litmus paper red. Generally, oxides of non-metals are acidic in nature.

Iodine is a non-metal which is used to make purple colored solution called “Tincher Iodine” which is applied on cuts and wounds as an antiseptic.

A substance which cannot be broken down into two or more simpler substances by chemical reaction is called an element. The smallest particle of an element is called atom. An element is a substance which is made up of only one kind of atoms. The atoms of an element remain unaffected by the physical changes in the element. Thus, an atom of liquid sulphur or vapour forms of sulphur would be same as that of solid sulphur.