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.

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

Sulphur is a non-metal and it forms an acidic oxide i.e. Sulphur Dioxide (SO2), which turns blue litmus red.

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.

When a copper object is exposed to moist air for a long time then copper reacts with water, carbon dioxide and oxygen present in moist air to form a green coating on the copper object. The green coating or green material is a mixture of copper hydroxide and copper carbonate which is formed by the action of moist air on copper object. The green coating of copper is also known as basic copper carbonate because it is basic in nature.

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.

Diamond is that non-metal which is a good conductor of heat. Graphite are non-metal which is a good conductor of heat, not sulphur. Iodine is a type of non-metal which having luster, (not sulphur and phosphorus).

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

Mercury metal is in the liquid state at room temperature.

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

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

Ductility is a characteristic property of metals. Sulphur is a non-metal, so it is not ductile. When stretched, sulphur break into pieces and do not form wires.

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

Most of the non-metals from acidic oxides but there are some exceptions. This is because some of the non-metals form neutral oxides which is neither acidic or basic. For example, hydrogen is a non-metal which forms a neutral oxide as H2O which is commonly known as water.

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.

Some metal reacts with base to form salts and hydrogen gas. Aluminum is a metal and sodium hydroxide is a base. When aluminum is heated with sodium hydroxide solution then sodium aluminate (salt) and hydrogen gas are formed. Zinc metal also reacts with sodium hydroxide solution to form hydrogen gas. Although, aluminum and zinc are the two common metals which react with base (like sodium hydroxide) to produce hydrogen gas. In general, we can say that some metals react with “Sodium Hydroxide” to produce hydrogen gas. But all the metals do not react with bases like “Sodium Hydroxide” to produce hydrogen gas.

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.