Which of the following is radioactive in nature?

Which of these gases is released upon treating zinc with diluted and then concentrated nitric acid?

What is the structure of phosphine?

What is the liquid product formed on decomposition of PCl5?

What is the source of obtaining oxygen industrially?

What is the catalyst used in contact process in the conversion of Sulphur dioxide to Sulphur trioxide?

Which of the following statements regarding group 16 elements is not true?

Why is helium added to oxygen which is used by deep-sea divers?