In the context of air pollution measurements, what does "PM2.5" refer to? 

What is the shape of the Milky Way galaxy?

Which company launched the inaugural batch of satellites with "Direct-to-Cell" technology?

Mycorrhiza is a symbiotic association between:

Who predicted the existence of the plunging region around black holes?

Rustom-2 is a/an __________ developed by India's Defence Research and Development Organisation (DRDO).

Which one is the largest Island of Japan?

Choose the correct statements regarding the process of photosynthesis. 

Which name is commonly used for "Sirius," the brightest star visible outside our solar system?