In the embryonic stage,$RBC$s develop in:

Menstrual flow occurs due to lack of

Which of the following is a polyamide?

What is the common name of benzene$-1,3-$diol?

Three non-zero non-collinear vectors $\vec{a}, \vec{b}$ and $\vec{c}$ are such that $\vec{a}+3\vec{b}$ is collinear with $\vec{c}$,and $3\vec{b}+2\vec{c}$ is collinear with $\vec{a}$. Then $\vec{a}+3\vec{b}+2\vec{c}$ equals to

In Earthworm,the dorsal wall of the intestine from the $26^{th}$ segment to the $95^{th}$ segment forms a median internal fold called: