All Free Everyday Science MCQs with Answers

641. As one moves away from the surface of earth with higher altitude ,the atmospheric pressure will go on ________.

• A. Increasing
• B. Decreasing
• C. Remains same
• D. First decreases then increases

Explanation: Atmospheric pressure decreases with altitude because there is less air above exerting weight on a given area. This is why breathing becomes more difficult at very high elevations.

642. Burning of Fossil Fuels Results In ____________?

• A. Increased oxygen level
• B. Decreases greenhouse gases
• C. Increased greenhouse gases
• D. Increased ethane level

Explanation: Burning coal, oil and gas releases carbon dioxide and other gases that increase the atmospheric greenhouse effect. It does not increase oxygen, and the relevant rise is mainly in carbon dioxide rather than ethane.

643. The height at which atmospheric pressure declines by a factor of e (an irrational number equal to 2.71828) is called __________.

• A. Average height (H)
• B. Scale height (H)
• C. Mean height (H)
• D. Standard height (H)

Explanation: The scale height is the vertical distance over which atmospheric pressure falls to 1/e, or about 36.8%, of its original value. It depends on temperature, gravity and the mean molecular mass of the air.

644. Exosphere interacts with ___________ of Earth at roughly distance of 10,000 km.

• A. Electrosphere
• B. Magnetosphere
• C. Spectrosphere
• D. Echosphere

Explanation: The outer exosphere merges gradually with space and interacts with Earth's magnetosphere, the region controlled by the planet's magnetic field. The other listed “spheres” are not recognised atmospheric regions.

645. __________ contains the ozone layer.

• A. Troposphere
• B. Stratosphere
• C. Mesosphere
• D. Ionosphere

Explanation: The stratosphere contains the concentrated ozone layer, generally about 15–35 km above Earth's surface. Ozone there absorbs ultraviolet radiation and causes temperature to increase with altitude.

646. __________ is the atmospheric layer wherein the weather occurs.

• A. Troposphere
• B. Stratosphere
• C. Mesosphere
• D. Thermosphere

Explanation: Most weather occurs in the troposphere because it contains most atmospheric water vapour and is heated from Earth's surface, producing convection, clouds and storms. The higher layers are much drier and more stable.

647. Atmospheric pressure is the force (per unit-area) perpendicular to a unit-area of planetary surface, as determined by _________.

• A. Mass of vertical column of atmospheric gases
• B. Mass of horizontal column of atmospheric gases
• C. Weight of vertical column of atmospheric gases
• D. Mass of vertical and weight of horizontal of atmospheric gases

Explanation: Atmospheric pressure is caused by the weight of the vertical column of air above a surface area. Mass alone is not a force, whereas weight is the gravitational force acting on that mass.

648. ___________ begins at 690 to 1,000 km from the surface, and extends to roughly 10,000 km.

• A. Troposphere
• B. Mesosphere
• C. Exosphere
• D. Stratosphere

Explanation: The exosphere is the outermost atmospheric layer, beginning roughly 690 to 1,000 km above Earth and extending thousands of kilometres into space. The troposphere, stratosphere, and mesosphere are much lower layers.

649. Which of the following is true about Ionosphere?

• A. Its density is lesser at short distances from planetary surface in morning and further decreases as ionosphere rises at night-time, thereby allowing a greater range of radio frequencies to travel greater distances
• B. Its density is greater at short distances from tplanetary surface in daytime and decreases as ionosphere rises at night-time, thereby allowing a greater range of radio frequencies to travel greater distances
• C. Its density is greater at long distances from planetary surface in daytime and further increases as ionosphere rises at night-time, thereby allowing a greater range of radio frequencies to travel greater distances
• D. None of the above

Explanation: The ionosphere is denser in its lower regions during daytime because solar radiation produces more ions, while reduced ionisation at night changes its height and radio-reflection behaviour. This simplified description matches option b; the actual ionosphere varies across several layers and frequencies.

650. Atmosphere is held in place by?

• A. Pressure of the planetary body
• B. Gravity of the planetary body
• C. Charge of the planetary body
• D. Heat of the planetary body

Explanation: Gravity pulls atmospheric gases toward a planet and prevents most of them from escaping into space. Pressure, charge, and heat can affect the atmosphere, but they do not hold it in place as gravity does.