Olimpiade Sains Nasional 2024

As is known together that the earth is stated to have formed about 4.5 billion years ago. Data supporting this fact can be obtained from ...

• dating of meteorites

• determination of the earth's magnetic field position

• calculations based on the cooling rate of the earth's crust

• measuring the thickness of sedimentary rock layers

• the age of the oldest fossils found on the earth's surface

The image shows a series of Hawaiian islands in the Pacific Ocean formed by volcanoes due to a hotspot. The arrows indicate the direction of the movement of the Pacific tectonic plate. Which statement is true regarding the age of volcanic rocks in the series of volcanic islands?

• The rocks in the series of volcanoes have the same age.

• The volcanic rocks from Hawaii to the volcano in Kauai are getting older.

• The volcanic rocks from Hawaii to the volcano in Kauai are getting younger.

• There is a random distribution of rock ages on the islands.

• The age of the rocks is difficult to determine.

The term partial melting is often encountered in discussions related to processes in subduction zones. The following statement regarding partial melting is correct ...

• Some rocks melt to form magma with the same composition as the original rock, leaving a residue with the same composition as the original rock.

• Some rocks melt to form magma with the same composition as the original rock, but leave a residue with a composition different from the original rock.

• Some rocks melt to form magma with a composition different from the original rock, and leave a residue with a composition different from the original rock.

• Some rocks melt to form magma with a composition different from the original rock, but leave a residue with the same composition as the original rock.

Part of the body of a volcano referred to as sill and vent pipe is number ...

• 6 and 10

• 1 and 3

• 5 and 3

• 6 and 12

• 1 and 6

Mica is one of the mineral groups. The incorrect statement about mica is ...

• is a silicate mineral

• has characteristics like sheets

• can contain elements K, Ca, Na, Al or Mg

• only forms in metamorphic rocks

• one example of the mineral is muscovite

Halite and gypsum are both evaporite minerals. If someone finds a gypsum layer in a rock outcrop, then the correct statement below is ...

• This area was once volcanically active.

• That area was once covered by seawater.

• The area used to be an active mountain region.

• That area was once buried deep under other rock layers.

• That area has experienced very strong tectonics.

Granite, andesite, and basalt are three types of igneous rocks. These rocks are classified into categories based on ...

• age of formation

• location where they formed

• texture and chemical composition

• size of the magma body from which they originated

• crystal structure of the minerals that compose them

Why are volcanic eruptions with basic magma generally less explosive compared to eruptions with acidic magma?

• Basic magma is hotter, so gas remains dissolved in the magma.

• Basic magma is denser, so gas cannot rise to the surface.

• Basic magma is richer in iron, keeping gas in crystalline phase.

• Acidic magma is denser, allowing gas to escape easily.

• Basic magma is more fluid, allowing gas to escape before reaching a certain pressure.

Mechanical weathering plays a role in the early formation of sedimentary rocks by ...

• heating sediments and allowing them to lithify faster.

• depositing minerals in the pore spaces between sediment grains.

• breaking down the bedrock into small fragments that will be carried by wind and water.

• removing dissolved components of the bedrock so ions can be transported by water and deposited elsewhere.

• helping plant roots enter the gaps between rocks.

The following photo shows the ripple mark structure on sediment at a beach. If a trench is made perpendicular to the ripple mark line, then the sediment section observed will be ...

• graded bedding

• flute casts

• cross beds

• mud cracks

• load casts