Class 8 Science Chapter 12 MCQ

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

An electroscope is a device, which is used to test whether an object is charged or not. It consists of closely place two metallic strips. When both the strips are charged with similar charges, they repel each other and become wide open.

Here, all are insulators whereas “Copper rod” is a conductor. As soon as we charge a copper rod by rubbing with another material, the electric charge flow through our hand and body and flows into the earth. As a result, the copper rod remains un-charged.

Two bodies must be joined by any conducting wire i.e., copper wire for the flow of current.

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

The electric charges generated by rubbing are static electric charges. There are two types of charges; “Positive Charge and Negative Charge”. All the objects like glass rod, silk cloth, rubber balloon, ballpoint pen etc., are made up of tiny particles called atoms. We know that positive electric charges called protons and negative electric charge is called electrons. The object which loses negatively charged electrons during rubbing, acquires a positive electric charge. The object which gains negatively charged electrons during the rubbing, acquires a negative electric charge.

Two charged objects may attract, if they carry opposite charges, while they repel. If they carry similar charges.

Benjamin Franklin is the scientist who showed that lightening is electric in nature. He discovered many things about lightening and was the first to show that a thunderstorm lets out electricity.

After rubbing the glass rod with silk cloth, the glass rod becomes positively charged. The silk cloth becomes negatively charged. When a plastic comb is dry hair, it becomes negatively charged. The negatively charged comb induces a positive charge on the pieces of paper which are neutral in nature.

An earthquake is a sudden shaking or trembling of the earth which lasts for a very short time. It is caused by the disturbance deep down inside the uppermost layer of the earth called crust.

The magnitude (or intensity) of an earthquake is expressed in terms of Richter scale.

Since earthquakes are caused by the movement of plates, the boundaries of the plates are weak zones where earthquake are more likely to occur. These weak zones are also known as seismic zones or fault zones.

The magnitude of an earthquake is expressed on the Richter scale. Richter scale is just like the decibel scale. But remember, it is not a linear scale. This means that an earthquake of magnitude 2 on Richter Scale is not 2 times as strong as an earthquake of magnitude 1. An earthquake of magnitude 2 is 10 times as strong as an earthquake of magnitude 1. An earthquake of magnitude 3 on Richter Scale is 100 times as strong as an earthquake of magnitude 1 on the same scale.

The outermost layer of the earth is called “crust”. It is also known as earth’s crust.

The epicentre is the point on the “earth’s surface” vertically above the hypocentre (or focus), point in the crust where a seismic rupture begins.

During a charging by rubbing (or by friction) process, the material that becomes negatively charged does so because it simply likes or gain electrons more than the material with which it is rubbed. The conductive abilities of the two materials has nothing to do with the subsequent result of the rubbing process.

Earthquake is a sudden shaking or trembling of the earth due to the collision between the earth’s plate or brushing past of one plate over the other. It can cause Tsunami, floods and landslides.

The process of electric discharge occurs between the earth and the clouds and ultimately leads to the lighting.

When we comb dry hair with plastic comb, friction takes place between two objects. Due to friction, hair losses some electrons to plastic comb. Due to loss of electron, the hair becomes positively charged and due to gain of electron, plastic comb becomes negatively charged.

A charged balloon and a charged ballpen refill having unlike charges or different charges, they attract each other. Remember, unlike charges are also called opposite charges. So, opposite charges attract each other.

A ballpoint pen refill can be charged by rubbing it against the wool cloth. It becomes negatively charged.

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

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

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

The whole crust of the earth is not in one piece. The crust of earth is made up of many huge pieces of flat rocks. Each pieces of the earth crust is called a plate. The crust of earth is divided into many plates. The plates of earth on which continents exist are called “continental plates” whereas those plates of earth on which oceans exist are called “oceanic plates”.