Which of the following is not a Lewis acid?

Which of the following is $NOT$ produced by the reaction of ethanol with $H_2SO_4$?

How many cyclic structures are possible for $C_4H_6$?

Work done in increasing the size of a soap bubble from a radius of $3\, cm$ to $5\, cm$ is nearly (Surface tension of soap solution $= 0.03\, Nm^{-1}$). (in $\pi \,mJ$)

$A$ transistor is used as an amplifier in $CB$ mode with a load resistance of $5 \; k\Omega$. The current gain of the amplifier is $0.98$ and the input resistance is $70 \; \Omega$. The voltage gain and power gain respectively are:

Which of the following salts increases the rate of the setting process of Plaster of Paris?