Early and modern theories

Correct answer: C. It explains observations, physical laws, and planetary composition together

The modern model connects many evidences and processes together. In exams, link scientific value with evidence and explanatory power.

Correct answer: A. Gravitational concentration

Kant imagined gaseous matter concentrating by gravity. In exams, connect Kant with a natural gravitational explanation.

Correct answer: D. The full physical process of stable ordered planets forming from rings was not clear

Laplace's idea was historically important, but its modern physical explanation was incomplete. In exams, write both contribution and limitation.

Correct answer: B. As the process of accretion

The joining of small bodies matches the modern idea of accretion. In exams, identify useful parts of old ideas.

Correct answer: A. Such a close event is extremely rare and ordered planetary orbits are hard to explain

The tidal theory is weakened by rarity and orbital-order problems. In exams, write both probability and orbit limitations.

Correct answer: A. Hot matter is difficult to condense into stable planets

Expansion of extremely hot matter and formation of stable planets is a major problem. In exams, connect physical behavior with limitation.

Correct answer: B. Source material was linked with interstellar gas and dust

Schmidt linked planet formation with interstellar material such as gas and dust. In exams, identify the source-material difference.

Correct answer: A. An attempt to explain planet formation through dynamic organization of matter in the nebula

The vortex idea was linked with motion and organization of matter within the nebula. In exams, connect Weizsäcker with modern planet-origin ideas.

Correct answer: A. Rotation, gravitational collapse, and conservation of angular momentum

A rotating cloud becomes a flat disk during collapse. In exams, link disk origin with rotation and gravity.

Correct answer: B. All planets formed from the original motion of the same rotating disk

Bodies formed from the same rotating disk show similar motion. In exams, connect similar direction with common source.

Correct answer: C. Composition of rocky inner planets and gaseous-icy outer planets

Beyond the frost line, accumulation of ice and gases was more possible. In exams, write distance, temperature, and composition together.

Correct answer: A. Rocky materials remained in the warm inner region and ice and gas were more common in the cold outer region

Temperature differences affected planetary material and size. In exams, connect temperature gradient with planetary composition.

Correct answer: A. They removed light gases and strengthened conditions for rocky planets

Solar winds reduced light gases in the inner region. In exams, also link the rocky nature of inner planets with solar winds.

Correct answer: A. Icy cores formed in cold regions and greater mass attracted gases

Cold outer regions and more material made gas giants large. In exams, remember cold region and stronger gravity together.

Correct answer: C. Possibility of planet formation from protoplanetary disks

Disks around young stars match the modern planet-formation model. In exams, treat such observations as support for the solar nebula idea.

Correct answer: C. They indicate leftover construction material of the solar system

Remnant bodies give information about early solar-system material. In exams, treat them as remnant clues of planet formation.

Correct answer: B. Red shift, recession of galaxies, expansion of universe

Red shift indicates receding galaxies. In exams, write the reasoning from evidence to conclusion.

Correct answer: A. It is like leftover radiation from the early hot universe

This radiation points to an early hot state. In exams, also remember it as a challenge to steady state theory.

Correct answer: A. Expansion spread energy through a larger volume, so temperature decreased

In the Big Bang model, the early universe was extremely hot and dense. As space expanded, the same general energy became distributed through an increasingly larger volume, and the average temperature fell. This expansion and cooling allowed particles, atoms and later larger structures to form. Hence option A gives the relevant cosmological relationship. Rivers, a static universe and the disappearance of the Sun are unrelated conclusions.

Correct answer: A. They became basic matter for later stars and galaxies

Light elements were early material of cosmic chemical evolution. In exams, remember basic matter before large bodies.

Correct answer: A. To keep average density constant despite expansion

The steady state theory imagined new matter forming during expansion. In exams, keep average density and continuous creation together.

Correct answer: C. Cosmic microwave background radiation

Background radiation was considered evidence of the early hot universe. In exams, write it in favor of the Big Bang.

Correct answer: A. Big Bang, galaxy formation, solar nebula, Earth accretion

First the universe, then galaxies, then the solar system and Earth formed. In exams, remember the order from larger to smaller scale.

Correct answer: A. Accretion adds mass and differentiation forms layers according to density

Accretion builds the planetary body and differentiation forms its internal structure. In exams, match process and function correctly.

Correct answer: A. Core

Heavy metallic materials moved to the center and helped form the core. In exams, connect iron-nickel with the core.