General Science Basics: questions and answers
Study every question with its correct answer and explanation.
1. What is the chemical symbol of sodium?
- A. So
- B. Na
- C. S
- D. Sd
Answer: Na
Sodium's symbol Na comes from its Latin name 'natrium'. Similarly, potassium is K (from 'kalium') and iron is Fe (from 'ferrum').
2. Which cell organelle is known as the 'powerhouse of the cell'?
- A. Nucleus
- B. Ribosome
- C. Mitochondria
- D. Golgi apparatus
Answer: Mitochondria
Mitochondria carry out cellular respiration and produce ATP, the cell's energy currency. Ribosomes, by contrast, are the sites of protein synthesis.
3. Which gas makes up the largest share of Earth's atmosphere?
- A. Nitrogen
- B. Oxygen
- C. Carbon dioxide
- D. Argon
Answer: Nitrogen
Nitrogen makes up about 78% of dry air, while oxygen makes up about 21%. Argon is the third most abundant gas at just under 1%.
4. What is the SI unit of force?
- A. Joule
- B. Watt
- C. Pascal
- D. Newton
Answer: Newton
Force is measured in newtons, where 1 N is the force that gives a 1 kg mass an acceleration of 1 m/s². The joule is the unit of work and energy, the watt of power, and the pascal of pressure.
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5. What is the pH of pure water at 25 °C?
- A. 0
- B. 7
- C. 10
- D. 14
Answer: 7
Pure water at 25 °C is neutral with a pH of 7. Solutions with a pH below 7 are acidic and those above 7 are basic (alkaline).
6. Deficiency of which vitamin causes scurvy?
- A. Vitamin A
- B. Vitamin D
- C. Vitamin C
- D. Vitamin K
Answer: Vitamin C
Scurvy, marked by bleeding gums and poor wound healing, is caused by a lack of vitamin C (ascorbic acid), found in citrus fruits and amla. Vitamin D deficiency causes rickets in children, and vitamin A deficiency causes night blindness.
7. Which is the hardest naturally occurring substance?
- A. Diamond
- B. Iron
- C. Quartz
- D. Graphite
Answer: Diamond
Diamond is the hardest natural substance and is a crystalline form (allotrope) of carbon. Graphite is also an allotrope of carbon, but it is soft and, unlike diamond, conducts electricity.
8. Which is the largest planet in the Solar System?
- A. Saturn
- B. Earth
- C. Neptune
- D. Jupiter
Answer: Jupiter
Jupiter is the largest planet, a gas giant more massive than all the other planets combined. Mercury is the smallest planet and the one closest to the Sun.
9. What is the approximate speed of light in a vacuum?
- A. 3 × 10⁶ m/s
- B. 3 × 10⁸ m/s
- C. 3 × 10¹⁰ m/s
- D. 3 × 10⁵ m/s
Answer: 3 × 10⁸ m/s
Light travels at about 3 × 10⁸ m/s (roughly 3 lakh km per second) in a vacuum. At this speed, sunlight takes about 8 minutes 20 seconds to reach Earth.
10. Which gas do green plants release during photosynthesis?
- A. Carbon dioxide
- B. Nitrogen
- C. Oxygen
- D. Hydrogen
Answer: Oxygen
In photosynthesis, green plants use sunlight absorbed by chlorophyll to turn carbon dioxide and water into glucose, releasing oxygen. The oxygen released comes from the splitting of water molecules, not from carbon dioxide.