Plant (producer) → Insect (herbivore) → [M] (primary carnivore) → Snake (secondary carnivore) → Eagle (top carnivore)
The missing link M must be:
(A) Rabbit - incorrect (herbivore, doesn't eat insects)
(B) Wolf - incorrect (higher carnivore, wouldn't be eaten by snakes)
(C) Frog - correct (insectivorous and preyed upon by snakes)
(D) Ichthyophis - incorrect (a legless amphibian that snakes wouldn't typically eat)
Thus, the complete chain is:
Plant → Insect → Frog → Snake → Eagle
Plant → Insect → M → Snake → Eagle
Answer: (C) Frog
In this food chain, we are looking for an organism that:
The other options, such as Rabbit (which typically feeds on plants and is not usually preyed upon by snakes as often as frogs), Wolf (which is a carnivore and not part of this food chain), and Ichthyophis (a type of amphibian not as common in this context) are not suitable.
A block of certain mass is placed on a rough floor. The coefficients of static and kinetic friction between the block and the floor are 0.4 and 0.25 respectively. A constant horizontal force \( F = 20 \, \text{N} \) acts on it so that the velocity of the block varies with time according to the following graph. The mass of the block is nearly (Take \( g = 10 \, \text{m/s}^2 \)):
A wooden block of mass M lies on a rough floor. Another wooden block of the same mass is hanging from the point O through strings as shown in the figure. To achieve equilibrium, the coefficient of static friction between the block on the floor and the floor itself is