Earth Science

The most abundant color visible from Earth, especially when viewed from space, is blue due to the vast coverage of oceans. This makes blue the correct answer.

Metamorphic rocks are formed when existing rocks undergo changes in mineral composition or texture due to heat and pressure within the Earth, distinguishing them from sedimentary and igneous rocks.

The scientifically accepted approximate age of the Earth is about 4.54 billion years, based on radiometric age dating of meteorite material and Earth rocks.

The Moon is estimated to be about 4.51 billion years old, formed shortly after the Earth. This age is widely accepted based on radiometric dating of lunar samples. Option A is the closest and most accurate estimate among the given choices.

The Earth completes a full 360° rotation in approximately 24 hours (mean solar day). Dividing 24 hours by 360 degrees gives 24/360 = 0.0667 hours per degree, which equals 4 minutes per degree. This means the Earth takes about 4 minutes to rotate through 1° of longitude. Although the sidereal day (rotation relative to stars) is slightly shorter (about 23h 56m 4s), for practical purposes and timekeeping, the 4-minute figure is used. Therefore, the correct answer is C (4 Minutes).

The moon's gravitational pull is the primary cause of tides in the Earth's oceans, making it the most important effect of the moon on Earth. While the moon is involved in eclipses, those are not effects on Earth itself, and it does not cause weather changes or earthquakes.

The average salinity of ocean water is approximately 35 grams of salt per kilogram of seawater, which is a widely accepted standard value in oceanography.

The Earth's atmosphere is divided into layers primarily based on the vertical profile of air temperature, which changes with altitude and defines layers such as the troposphere, stratosphere, mesosphere, and thermosphere.

The mesosphere is the atmospheric layer located approximately between 50 km and 85 km above Earth's surface, making 85 km a correct reference for its upper boundary.

Earth is closest to the sun (perihelion) in early January, which corresponds to winter in the Northern Hemisphere. It is farthest from the sun (aphelion) in early July, during the Northern Hemisphere summer.