CBSE Class 10 Answered

Dry ice is solid carbon dioxide (CO₂), made by compressing and cooling gaseous CO₂ until it liquefies. It is possible to convert excess of CO₂ present in the atmosphere into dry ice and send it for disposal in outer space. This would certainly minimise the extent of global warming. However, the following limitations would make it barely possible to put this technique into use:

• It is not possible to estimate the quantity of excess of CO₂ gas present in the atmosphere. The concentration of CO₂ would vary from place to place.
• It would extremely difficult to collect this excess of CO₂ for conversion into dry ice.
• Some potential hazards and risks are associated with the handling, storage, transport and disposal of dry ice.
• In high concentrations, sublimed vapour may cause asphyxiation.
• Since dry ice has a product temperature of -78°C, it is a good source of extreme coldness but contact with the product can cause cold burns or frostbite.
• Sublimation of gaseous CO₂ results in the depletion of oxygen concentration in the air. 
• Depleted oxygen in the absence of an increase in carbon dioxide causes hypoxia which is extremely dangerous because the victim floats off into a euphoric sleepy state.

Therefore, due to these limitations it is not practically possible to convert excess of CO₂ into dry ice and survive normally. In fact, we have now evolved to react to increasing levels of carbon dioxide proportionately to oxygen depletion.