Into how many subclasses is the class $Dicotyledonae$ divided?

$A$ block of mass $m$ is placed on a smooth wedge of inclination $\theta$. The whole system is accelerated horizontally so that the block does not slip on the wedge. The force exerted by the wedge on the block ($g$ is acceleration due to gravity) will be

When $FeCl_3$ reacts with $K_4[Fe(CN)_6]$,which of the following compounds is formed?

After losing a number of $\alpha$ and $\beta$ particles,$_{92}U^{238}$ is changed to $_{82}Pb^{206}$. The total number of $\alpha$-particles lost in this process is:

If $\left|\begin{array}{cc}x & 2 \\ 18 & x\end{array}\right|=\left|\begin{array}{cc}6 & 2 \\ 18 & 6\end{array}\right|,$ then $x$ is equal to

Identify $acetaldoxime$.