Archegonia and antheridia in homosporous pteridophytes are present in:

$A$ Carnot engine whose low temperature reservoir is at $7^{\circ} C$ has an efficiency of $50 \%$. It is desired to increase the efficiency to $70 \%$. By how many degrees should the temperature of the high temperature reservoir be increased in $K$?

Which zone of the blast furnace has the highest temperature?

$A$ short magnetic needle is pivoted in a uniform magnetic field of induction $1 ~T$. Now,simultaneously another magnetic field of induction $\sqrt{3} ~T$ is applied at right angles to the first field; the needle deflects through an angle $\theta$ whose value is (in $^{\circ}$)

Two rain drops reach the earth with different terminal velocities having ratio $9:4$. Then the ratio of their volumes is

Plants are known as gymnosperms because -