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- Question
What is the third most common gas found in the air we breathe ?
Options- A. Argon
- B. Neon
- C. Carbondioxide
- D. Hydrogen
- Correct Answer
- Argon
ExplanationThe most common gas people breathe from clean air is nitrogen. Air is a mixture of gases, and the air on Earth contains about 78 percent nitrogen and about 21 percent oxygen. Argon, carbon dioxide neon, helium, methane, krypton, hydrogen and xenon are in much smaller amounts.
- 1. How many moles are there in 140g of Si (atomic mass of silicon is 28)
Options- A. 5
- B. 10
- C. 28
- D. 140 Discuss
- 2. When water freezes its density
Options- A. decreases
- B. remains constant
- C. increases
- D. become zero Discuss
- 3. Which one of the following elements is the poorest conductor of heat
Options- A. sodium
- B. lead
- C. zinc
- D. mercury Discuss
- 4. ' Misch metal ' is widely used in manufacture of which of the following
Options- A. Material of car brake
- B. Smoke detectors
- C. Cigarette lighters
- D. Emergency lights Discuss
- 5. How many electrons are there in Na+
Options- A. 1
- B. 10
- C. 11
- D. 12 Discuss
- 6. The metal which reacts most violently with with cold water is
Options- A. calcium
- B. sodium
- C. magnesium
- D. potassium Discuss
- 7. What is the element present in urea
Options- A. C,H,O
- B. C,N,O
- C. C,N,H
- D. C,O,N,H Discuss
- 8. In known elements, the maximum number is of
Options- A. Metals
- B. Non Metals
- C. Metalloids
- D. None of these Discuss
- 9. The nitrogen atom has 7 protons and 7 electrons,The nitride ion will have
Options- A. 10 protons and 7 electrons
- B. 7 protons and 10 electrons
- C. 4 protons and 7 electrons
- D. 4 protons and 10 electrons Discuss
- 10. Electromagnetic radiation with maximum wavelength is
Options- A. ultraviolet
- B. radio waves
- C. x-rays
- D. infrared Discuss
Chemistry problems
Search Results
Correct Answer: 5
Correct Answer: decreases
Explanation:
When water freezes its density decreases.
Water at ordinary temperatures contracts and increases in density as it is cooled, like most substances. But at about 4°C it reaches a maximum density and then decreases in density as it approaches the freezing point.
Correct Answer: lead
Correct Answer: Cigarette lighters
Correct Answer: 10
Correct Answer: potassium
Explanation:
Potassium reacts violently with water liberating hydrogen. The reaction is so violent that the liberated hydrogen catches fire.
Correct Answer: C,O,N,H
Correct Answer: Metals
Correct Answer: 7 protons and 10 electrons
Correct Answer: radio waves
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