Which hormone is produced by the placenta?

During which time interval is the particle described by these position graphs at rest?

If $\int \frac{7x^8+8x^7}{(1+x+x^8)^2} dx = f(x) + c$,then $f(x)$ is equal to

If $\cos (x-y), \cos x, \cos (x+y)$ are three distinct numbers which are in harmonic progression and $\cos x \neq \cos y$,then $1+\cos y$ is equal to

According to molecular orbital theory,the total number of bonding electron pairs in $O_2$ is

In the given $(V-T)$ diagram,what is the relation between pressure $P_1$ and $P_2$?