Which animal group possesses a pseudocoelom?

$A$ transverse wave is passing through a stretched string with a speed of $20 \ m/s$. The tension in the string is $20 \ N$. At a certain point $P$ on the string,it is observed that energy is being transferred at a rate of $40 \ mW$ at a given instant. Find the speed of point $P$.

An electron beam travels with a velocity of $1.6 \times 10^7 \ m/s$ perpendicularly to a magnetic field of intensity $0.1 \ T$. Calculate the radius of the path of the electron beam. (Given: $m_e = 9 \times 10^{-31} \ kg$,$e = 1.6 \times 10^{-19} \ C$)

$A$ satellite is revolving very close to a planet of density $\rho$. The period of revolution of the satellite is

An electric motor operating on a $60\,V$ $dc$ supply draws a current of $10\,A$. If the efficiency of the motor is $50\%$,the resistance of its winding is....$\Omega$

Which of the following does not act as a neurotransmitter?