EARTH SCIENCE PRE-TEST 2024-2025

Which is NOT true about the earth?

• revolves around the sun for 24 hours

• terrestrial planet

• has an atmosphere

• has 1 moon

Which layer of the atmosphere is the ozone layer found?

• exosphere

• stratosphere

• trophosphere

• mesosphere

Using Moh's scale, which among the minerals is the hardest?

• calcite

• corundum

• steel

• quartz

How much temperature is needed to melt the rock and extract the metal from the ore?

• Less than 50 degrees Celsius

• less than 100 degrees Celsius

• more than 900 degrees Celsius

• 900 degrees Celsius only

How much percent of saline water there is in the Earth relative to all the water as a whole?

• 70%

• 30%

• 96%

• 4%

Which of the following is a direct way in which human activities pollute water bodies?

• Volcanic eruptions releasing ash into rivers.

• Natural weathering of rocks leaching minerals into lakes.

• Discharge of untreated sewage into streams.

• Evaporation of water from agricultural fields.

Answer explanation

Untreated sewage contains various pollutants such as pathogens, organic matter, nutrients (like nitrogen and phosphorus), and sometimes toxic chemicals. When discharged into streams or other water bodies without proper treatment, it can degrade water quality and harm aquatic ecosystems and human health. Therefore, the discharge of untreated sewage is a direct way in which human activities pollute water bodies.

Which gas is produced at landfills?

• nitrogen

• hexane

• ethanol

• methane

Answer explanation

Methane is produced at landfills because organic waste undergoes anaerobic decomposition by bacteria, leading to the breakdown of carbon-containing materials into methane gas and carbon dioxide. The absence of oxygen in the landfill environment promotes the growth of methane-producing bacteria (methanogens), which convert organic matter into methane as a metabolic byproduct.

How is crop rotation done?

• the same crops are planted in an area within a year

• no crops are planted in an area within a year

• different crops are planted in an area within a year

• crops are transferred to different areas within a year

Answer explanation

Crop rotation is a farming practice where different crops are planted in the same field in sequential seasons or years. It helps to maintain soil fertility, reduce pest and disease pressure, and improve overall crop yield by varying nutrient demands and disrupting pest life cycles.

Where does the water of the earth come from?

• a comet which hit the earth

• an asteroid that collided with the earth

• the moon

• condensed water vapor from volcanic eruptions

Answer explanation

Water from Earth's interior can come from the condensation of water vapor emitted during volcanic eruptions. When magma rises towards the Earth's surface, it can carry dissolved water and other volatiles. Upon reaching lower pressures near the surface during eruptions, this water vapor can condense and contribute to volcanic eruptions' explosive nature and the formation of volcanic clouds.

What type of rock is formed from the solidification of lava at or near the Earth's surface?

• extrusive igneous

• metamorphic

• intrusive igneous

• sedimentary

Answer explanation

Extrusive igneous rocks form from the solidification of lava at or near the Earth's surface. Sedimentary rocks form from the accumulation of sediments, metamorphic rocks form from the alteration of existing rocks under heat and pressure, and intrusive igneous rocks form from the slow cooling of magma beneath the Earth's surface.