Acetylene is the only fuel gas suitable for gas welding because of its favourable flame characteristics of both high temperature and high propagation rates. Other fuel gases, such as propane, propylene or natural gas, produce insufficient heat input for welding but are used for cutting, torch brazing and soldering.

Low pressure – when reading of the barometer is lower than inHg, this is considered as low air pressure, which is associated with warm air and rainstorm. So, clearly, a falling barometer indicates bad weather is ahead.

The main function of epithelial tissue is:

(C) Defense

Explanation:

Epithelial tissue serves as a protective covering for the body and its organs. It acts as a barrier that helps prevent the entry of pathogens and other harmful substances. Epithelial cells are tightly packed and form continuous sheets, providing a protective layer on the body surfaces, both internal and external. This protective function is essential for defending the body against infections and maintaining its integrity. Therefore, option (C) Defense is the correct answer.