Which of the following hormones is a derivative of an amino acid?

Select the correct statement:

The cause of the potential barrier in a $P-N$ junction diode is

Acetic acid is reacted with metallic sodium to form hydrogen and $X$. When $X$ is heated with sodalime,$Y$ and sodium carbonate are formed. $Y$ is

The number of nodal planes in a $p_x$ orbital is

If the curves $y^2=6x$ and $9x^2+by^2=16$ intersect each other at right angles,the value of $b$ is