In India,the technology of biogas production was developed mainly by the efforts of which organizations?

Mohan was writing a report on the benefits of biogas:
$i$. It is cheap and safe
$ii$. Can be used for cooking
$iii$. Can be transported easily
$iv$. Causes pollution
Which one of the above statements has been reported incorrectly?

What does the part labeled '$X$' in the given figure represent?

Which plant is important from an economic and sanitation perspective in rural areas?

Consider the following statements about methanogenic bacteria:
$I.$ Methanogenic bacteria are commonly found in the anaerobic sludge formed during sewage treatment.
$II.$ These bacteria also occur in the rumen of cattle,where they act upon cellulosic material to break down cellulose.
$III.$ They play a very important role in the nutrition of cattle by digesting cellulosic material.
Which of the statements given above are correct?

In the given diagram of a biogas plant,what do '$Q$' and '$S$' represent?