When two different halogens react with each other, interhalogen compounds are formed. They can be assigned general compositions as XX’ , XX’_3, XX’₅ and XX’₇ where X is halogen of larger size and X’ of smaller size and X is more electropositive than X’. As the ratio between radii of X and X’ increases, the number of atoms per molecule also increases. Thus, iodine (VII) fluoride should have maximum number of atoms as the ratio of radii between I and F should be maximum. That is why its formula is IF₇ (having maximum number of atoms).

What do asthma patients use for respiration?

O₂ and He

The correct answer is option 2. O₂ and He.

Asthma patients primarily use oxygen \((O_2)\) for respiration. During asthma attacks or periods of breathing difficulty, the airways become inflamed and narrowed, making it harder to breathe. Oxygen therapy helps ensure that the body receives an adequate supply of oxygen, which is essential for the proper functioning of cells, tissues, and organs.

While oxygen therapy is the primary treatment for asthma-related breathing difficulties, the use of helium \((He)\) in combination with oxygen has also been explored in certain cases. Helium is less dense than air and has lower viscosity, allowing it to flow more easily through narrow airways. This property of helium can help reduce the work of breathing and improve airflow in individuals with severe asthma attacks or respiratory distress.

However, the use of helium-oxygen mixtures (heliox) is typically reserved for more severe cases and is administered under medical supervision. It's not as commonly used as pure oxygen therapy for asthma patients.

So, while oxygen \((O_2)\) is the primary choice for asthma patients for respiration, helium-oxygen mixtures (\(O_2\) and \(He\)) may be considered in certain severe cases to help improve airflow through narrowed airways.