Hourly Challenge · Science
🕐 31 Oct 2026 · 12 PM IST
5 questions · 20 seconds each · instant explanations. For PSC, UPSC, SSC, Banking & Railway aspirants. No login needed.
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20s
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Question 1 / 5Score: 0
Which gas is most abundant in the Earth's atmosphere?
Explanation: Nitrogen makes up about 78% of dry air by volume, while oxygen is about 21% and argon about 0.93%.
Question 2 / 5Score: 0
What is the SI unit of electric resistance?
Explanation: Resistance is measured in ohms (Ω), named after Georg Simon Ohm. By Ohm's law, R = V / I.
Question 3 / 5Score: 0
Deficiency of which vitamin causes scurvy?
Explanation: Scurvy is caused by a lack of vitamin C (ascorbic acid), which the body needs to make collagen. Symptoms include bleeding gums and slow wound healing.
Question 4 / 5Score: 0
Which organelle is known as the 'powerhouse of the cell'?
Explanation: Mitochondria carry out cellular respiration and produce most of the cell's ATP, the energy currency of the cell.
Question 5 / 5Score: 0
What is the chemical formula of common salt?
Explanation: Common salt is sodium chloride, NaCl. Na2CO3 is washing soda and NaHCO3 is baking soda.
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