For a normal eye,the cornea of the eye provides a converging power of $40 \ D$ and the least converging power of the eye lens behind the cornea is $20 \ D$. Using this information,the distance between the retina and the cornea-eye lens can be estimated to be.......... $cm$.

$A$ population $p(t)$ of $1000$ bacteria introduced into a nutrient medium grows according to the relation $p(t) = 1000 + \frac{1000t}{100 + t^2}$. The maximum size of this bacterial population is

If $y = (\sin x)^{\tan x}$,then $\frac{dy}{dx}$ is equal to

Three moles of an ideal monoatomic gas undergo a cyclic process as shown in the figure. The temperatures of the gas in different states marked as $1, 2, 3$ and $4$ are $400 \ K, 700 \ K, 2500 \ K$ and $1100 \ K$ respectively. The work done by the gas during the process $1-2-3-4-1$ is (universal gas constant is $R$): (in $R$)

Which of the following $statement(s)$ is/are not correct?
$(i)$ Reproduction is the production of progeny possessing features dissimilar to their parents.
$(ii)$ The fungi,the filamentous algae,the protonema of mosses,all multiply by budding.
$(iii)$ Many organisms like mules,sterile worker bees do not reproduce.
$(iv)$ Reproduction is not an all-inclusive defining characteristic of living organisms.

If the number of $5$-element subsets of the set $A = \{a_1, a_2, \ldots, a_{20}\}$ of $20$ distinct elements is $k$ times the number of $5$-element subsets containing $a_4$,then $k$ is