Eutrophication results in the reduction of

Two lakes,$A$ and $B$ are identical in all aspects except that lake $A$ has higher temperature. Which of the following is true?

What is the amount of oxygen consumed by bacteria to oxidize all the organic matter present in one liter of water called?

Fly-ash is a/an :

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

Why is $CNG$ considered a better fuel than diesel/petrol?
$I.$ $CNG$ burns most efficiently without leaving any unburnt remnant behind.
$II.$ $CNG$ is cheaper than petrol or diesel.
$III.$ $CNG$ cannot be siphoned off by thieves and adulterated like petrol or diesel.
Which of the statements given above are correct?