Wednesday, June 5, 2013

Earth Science Book 9th Grade

Earth science

Earth science (also known as geo science, the geo sciences or the Earth sciences), is an all-embracing term for the sciences related to the planet Earth. It is arguably a special case in planetary science, the Earth being the only known life-bearing planet. There are both reductionist and holistic approaches to Earth sciences. The formal discipline of Earth sciences may include the study of the atmosphere, oceans and biosphere, as well as the solid earth.

Earth's interior

Beneath the Earth's crust lies the mantle which is heated by the radioactive decay of heavy elements. The mantle is not quite solid and consists of magma which is in a state of semi-perpetual convection. This convection process causes the lithe spherical plates to move, albeit slowly. The resulting process is known as plate tectonics.

 Plate tectonics might be thought of as the process by which the earth is resurfaced. Through a process called spreading ridges , new earth crust is created by the flow of magma from underneath the lithosphere to the surface, through fissures, where it cools and solidifies. Through a process called subduction, crust is pushed underground—beneath the rest of the lithosphere—where it comes into contact with magma and melts—rejoining the mantle from which it originally came.

Areas of the crust where new crust is created are called divergent boundaries, and areas of the crust where it is brought back into the earth are called convergent boundaries. Earthquakes result from the movement of the lithe spherical plates, and they often occur near convergent boundaries where parts of the crust are forced into the earth as part of subduction.

Volcanoes result primarily from the melting of subducted crust material. Crust material that is forced into the Astheno sphere melts, and some portion of the melted material becomes light enough to rise to the surface—giving birth to volcano.

Earth's spheres
Earth science generally comprises of four spheres, the lithosphere, the hydrosphere, the atmosphere, and the biosphere; these correspond to rocks, water, air, and life. Some practitioners include, as part of the spheres of the Earth, the cryo sphere (corresponding to ice) as a distinct portion of the hydrosphere, as well as the pedo sphere (corresponding to soil) as an active and intermixed sphere.

Earth's electromagnetic field
An electromagnet is a magnet that is created by a current that flows around a soft-iron core. Earth has a soft iron core surrounded by semi-liquid materials from the mantle that move in continuous currents around the core; therefore, the earth is an electromagnet. This is referred to as the dynamo theory of Earth's magnetism. The fact that Earth is an electromagnet helps it maintain an atmosphere suitable for life.

know more about this click here Anthropogenic Greenhouse Gases And Eutrophication Causes

Wednesday, May 29, 2013

Middle School Science Test Questions


Introduction to middle school science test questions:

The word Science is formed from the Latin word 'Scientia' which means "knowledge". Thus science is an enterprise of gathering knowledge and then organizing that knowledge into laws and theories. Literacy in Science is the ability of the people to understand the basic concepts related to science.

Science can be classified into 3 main parts - Physics, Chemistry, Biology.
middle school science test questions


Middle School Science Test Questions



Q1. How do you know that a pet animal is sick? Write down any six symptoms.

Answer:

Symptoms of sick pet animal

(i) Animals feel laziness and weakness.

(ii) It can have high fever.

(iii) There may be smell in stool.

(iv) There is loss of water from eyes and nose.

(v) It does not eat properly.

(vi) There may be shivering.

Q2. What is vaccination?

Answer:

Vaccination: It is a process of injecting a substance (vaccine) into a healthy person in order to develop immunity against a specific disease.

Q3. Explain three effects of soil erosion.

Answer: Soil erosion produces many bad effects such as:

1. Loss of fertility due to removal of top fertile layers of soil.

2. Siltation of river beds, lakes, dams and plains along river banks.

3. Loss of forest vegetation.

Q4. Define humus.

Answer:

Humus:  The dark black coloured material, which is formed by decomposition of dead organisms and waste material, is known as humus. Its presence increases the fertility of soil.

Q5. Write four uses of methane

Answer:

Four uses of methane:

1. It is used as fuel for cooking food.

2. It is used for manufacturing fertilizers.

3. Methanol is prepared from methane.

4. It is used to prepare lamp black and many other organic compounds.


More Middle School Science Test Questions


Q6. What is all otropy? Give two examples.

Answer: The property due to which a chemical element exists in two or more different forms having similar chemical properties is called all o trophy. These forms are called all o tropes.

Carbon and Phosphorus are the examples to exhibit this property.

Q7. What is galvanization?

Answer: In this process, the iron object to be galvanized is first cleaned thoroughly and then dipped in molten zinc. Thus the object is galvanized and prevented from getting corroded.

Q8. How would you reduce green house effect?

Answer:

Reduction of green house effect: The following remedies can be taken to reduce green house effect:

1. The most obvious is to reduce the amount of fossil fuel burning, either through energy conservation or by introduction of alternative energy sources.

2. It might be possible to filter CO2 from power station emissions, convert it to other chemical forms and dispose it off in places other than the atmosphere, such as oceans.

3. Planting more trees may reduce the CO2 content in the atmosphere. So reforestation programmes have been launched.

4. The society should accept the changing climate.

Q9. What is the reason that we see a pencil broken when half dipped in water?

Answer: This is due to refraction of light. The rays coming from the lower points of the pencil bend away from the normal at the surface of water and we see raised pencil dipped in water. So it looks broken or bent.

Q10. What is angle of deviation?

Answer: The angle which incident ray makes with the emergent ray is called Angle of deviation i.e. the angle between incident ray and the emergent ray is called angle of deviation.

Note: If you require more help with middle grade science tet questions, our group of qualified tutors will help you in achieving that.

If you want to know more clarification click here What are Greenhouse Gases And Chemical Equations