Which of the following does not perform nitrogen fixation?

Myxoxanthophyll is found in

Which characteristics are included in the Kingdom $Monera$?

Which of the following may cause water blooms?

In the bacterium $Bacillus$ $subtilis$,the cells often become attached from end to end forming long filamentous chains,which are embedded in a mass of mucilage forming a scum layer on the substratum. This is called:

Match the organisms in Column-$I$ with habitats in Column-$II$.

Column-$I$	Column-$II$
$(a)$ Halophiles	$(i)$ Hot springs
$(b)$ Thermoacidophiles	$(ii)$ Aquatic environment
$(c)$ Methanogens	$(iii)$ Guts of ruminants
$(d)$ Cyanobacteria	$(iv)$ Salty area

Select the correct answer from the options given below: