Multiple choice

Which of the following statements is correct?

  1. Carbon dioxide allows the Earth to radiate heat rapidly at night.

  2. Percentage of carbon dioxide in air varies form 0.03% to 0.04%.

  3. Radon is not a cancer causing radioactive gas.

  4. A combustible substance combines with nitrogen to liberate heat energy.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

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