Which substance is used in refrigerators and air conditioners?

Which of the following is the correct match between List-$I$ and List-$II$?

List-$I$	List-$II$
$1.$ Producer	$a.$ Rabbit
$2.$ Herbivore	$b.$ Bear
$3.$ Carnivore	$c.$ Algae
$4.$ Omnivore	$d.$ Snake

Which of the following limits the number of trophic levels in a food chain?

In a food chain,the third trophic level is always occupied by

There are generally a greater number of individuals at the lower trophic levels of an ecosystem.

In the given figure,the various trophic levels are shown in the form of a pyramid. At which trophic level is maximum energy available and at which trophic level is the maximum number of organisms present?