Which of the following pairs of organs consists only of endocrine glands?

The correct formula of diammine dichlorodicyanochromate$(III)$ ion is

Gonadotropic hormones are produced by .....

Which of the following pairs of animals represents jawless fishes?

$A$ block of $200 \text{ g}$ mass moves with a uniform speed in a horizontal circular groove with vertical side walls of radius $20 \text{ cm}$. If the block takes $40 \text{ s}$ to complete one round,the normal force exerted by the side walls of the groove is:

$A$ wire elongates by $l \, mm$ when a load $W$ is hung from it. If the wire goes over a pulley and two weights $W$ each are hung at the two ends,the elongation of the wire will be (in $mm$)