NTS Pakistan Railways Everyday Science: Earth Science MCQs

NTS Pakistan Railways Everyday Science: Earth Science MCQs — sample questions

1. Question 1

   Q1. Which is the brightest planet in the solar system?

   • A) Mars
   • B) Venus
   • C) Jupiter
   • D) Mercury

   Answer: Venus

   Explanation: Venus is the brightest planet as seen from Earth due to its thick, highly reflective cloud cover that reflects about 70% of sunlight.

2. Question 2

   Q2. In a typical H-R diagram, stars are graphed by which two characteristics?

   • A) Luminosity and distance
   • B) Distance and temperature
   • C) Size and distance
   • D) Temperature and Luminosity

   Answer: Temperature and Luminosity

   Explanation: The Hertzsprung-Russell (H-R) diagram plots stars according to their luminosity (absolute brightness) on the y-axis and surface temperature (spectral class) on the x-axis.

3. Question 3

   Q3. How many planets are in our solar system:

   • A) 6
   • B) 7
   • C) 8
   • D) 9

   Answer: 8

   Explanation: Since Pluto was reclassified as a dwarf planet by the IAU in 2006, our solar system officially has eight planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.

4. Question 4

   Q4. Which gas in Chlorofluorocarbons damages the ozone layer most:

   • A) Chlorine
   • B) Fluorine
   • C) Ammonia
   • D) Bromine

   Answer: Chlorine

   Explanation: In CFCs, chlorine atoms are the primary ozone-depleting agents; a single chlorine atom can catalytically destroy thousands of ozone molecules in the stratosphere.

5. Question 5

   Q5. The ozone layer is at a height of ____ kilometers from the surface of the Earth.

   • A) 20 to 30
   • B) 30 to 40
   • C) 40 to 50
   • D) 10 to 20

   Answer: 20 to 30

   Explanation: The ozone layer is concentrated in the stratosphere at altitudes of approximately 20 to 30 kilometers above Earth's surface, where it absorbs harmful UV-B and UV-C radiation.