Early and modern theories

Correct answer: B. It tried to connect the solar system with a cloud of gaseous matter

Kant linked the origin of the Sun and planets with a gaseous nebula. In exams, identify similarities between old and modern ideas.

Correct answer: C. Contraction and faster rotation of the nebula

Laplace proposed rings separating from a contracting and rotating nebula. In exams, remember contraction, rotation, and ring together.

Correct answer: A. Emphasis on accumulation of small solid bodies

The planetesimal hypothesis explains planets forming from small solid planetesimals. In exams, accumulation of solid bodies is the key clue.

Correct answer: B. Expansion of very hot ejected matter and difficulty in forming stable planets

It is difficult to assume that hot matter drawn from the Sun could easily condense into stable planets. In exams, mention the physical limitation of the theory.

Correct answer: C. They formed in a flat protoplanetary disk

Bodies formed in a flat rotating disk move nearly in the same plane. In exams, connect orbital plane with the protoplanetary disk.

Correct answer: A. Only heavy and high melting point materials could remain near the Sun

Near the Sun, temperature was high, so light gases could not remain easily. In exams, treat inner planets as rocky and dense.

Correct answer: C. Greater accumulation of gas and ice in colder outer regions

Outer regions were colder, so gas and ice could remain in larger amounts. In exams, remember outer planets as gas giants.

Correct answer: D. Big Bang explains the universe and solar nebula explains the solar system

The Big Bang works at the universe scale, while the solar nebula works at the solar system scale. In exams, identify the scale first.

Correct answer: A. The universe is on average static and unchanging

Red shift indicated galaxies moving away and expansion of the universe. In exams, take it as evidence against a static universe.

Correct answer: B. It is considered a remnant signal of the early hot universe

This radiation gives strong support to the Big Bang theory. In exams, identify it as cosmological evidence.

Correct answer: A. Maintaining average density despite expansion

The steady state theory assumed new matter formed during expansion to keep average density constant. In exams, remember the link between expansion and continuous creation.

Correct answer: A. Because expansion distributes energy over a larger volume

Expansion made the early hot universe cool gradually. In exams, write expansion and temperature decrease together.

Correct answer: B. Because small bodies can join by gravity to form larger bodies

In accretion, joining of particles and planetesimals is the basis of planetary growth. In exams, connect collisions with growth too.

Correct answer: C. A planetesimal is a smaller building body while a protoplanet is a larger developing body

Planetesimals combine to form protoplanets, and a protoplanet may become a planet. In exams, remember size and developmental order.

Correct answer: B. Denser materials moved toward the center and lighter materials upward

In differentiation, heavy materials settled downward and lighter materials stayed above. In exams, connect core, mantle, and crust with density.

Correct answer: A. Both supplied heat and made differentiation possible

Impacts and radioactive heat kept early Earth in a molten state. In exams, link heat sources with differentiation.

Correct answer: A. Widespread photosynthetic life had not developed then

Free oxygen in the atmosphere increased later due to biological activity. In exams, keep early and present atmospheres separate.

Correct answer: A. Outgassing supplied gases such as water vapour whose condensation helped form the hydrosphere

Water vapour released by outgassing cooled and turned into water. In exams, study atmosphere and hydrosphere development together.

Correct answer: A. Differentiation and formation of layers

In the molten state, materials could separate according to density. In exams, remember molten Earth and differentiation together.

Correct answer: A. It suggests the Moon may have formed from material ejected after an impact with early Earth

The giant impact idea links Moon's origin with the active early Earth. In exams, treat it as a modern explanation.

Correct answer: A. Tidal theory - rarity of a passing star and problem of hot matter

The tidal theory has difficulties related to a passing star and condensation of ejected matter. In exams, match the correct limitation with the correct theory.

Correct answer: A. Cosmic microwave background radiation

Background radiation is a signal of the early hot universe. In exams, understand it as strong evidence against the steady state theory.

Correct answer: B. Accretion

This sequence shows the accretion process from smaller to larger bodies. In exams, identify the process from the sequence.

Correct answer: A. Angular momentum of the same original rotating nebula

Bodies formed from the same rotating cloud show similar direction of motion. In exams, connect common source and angular momentum.

Correct answer: B. A region of leftover or incomplete planet-forming material

The asteroid belt is linked with leftover construction material of the solar system. In exams, study it as a remnant region.