Which of the following does not act as a neurotransmitter?

Which of the following is an acidic salt?

Which of the following carbonyl compounds will exhibit enolization?
$(i)$
$(ii)$
$(iii)$
$(iv)$
$(v)$

$A$ bag $X$ contains $2$ white and $3$ black balls and another bag $Y$ contains $4$ white and $2$ black balls. One bag is selected at random and a ball is drawn from it. Then the probability for the ball chosen to be white is

$1\, g$ of hydrogen is converted into $0.993\, g$ of helium in a thermonuclear reaction. The energy released is

If the slope of one of the lines given by $ax^2+2hxy+by^2=0$ is two times the other,then: