For an ideal gas, which one of the following statements does not hold true?

Which one of the following gas smells like a rotten egg?

Which of the following represent the suitable condition for the liquefaction of gases?

Which one of the following greenhouse gases is present in the largest quantity in the atmosphere?

Which of the following gasses is/are lighter than air? 1. Hydrogen chloride 2. Sulfur dioxide 3. Helium

Bright light is found to emit from photographer's flashgun. This brightness is due to the presence of which one of the following noble gases?