Which of the following belongs to the series Gamopetalae?

The enthalpy of formation of ammonia is $-46.0 \ kJ \ mol^{-1}$. The enthalpy change for the reaction $2NH_{3(g)} \to N_{2(g)} + 3H_{2(g)}$ is ...... $kJ \ mol^{-1}$.

Consider the following reactions:
$3NiS + 2HNO_3 + 6HCl \rightarrow 3NiCl_2 + 2NO + 3S + 4H_2O$
$NiCl_2 + 2NH_4OH + 2(CH_3C(=NOH)C(=NOH)CH_3) \rightarrow B + 2NH_4Cl + 4H_2O$
The number of protons that do not involve in hydrogen bonding in the product $B$ is:

$A$ ball of mass $m$ and radius $r$ is gently released in a viscous liquid. The mass of the liquid displaced by it is $m'$ such that $m > m'$. The terminal velocity is proportional to

$A$ large open tank has two holes in the wall. One is a square hole of side $L$ at a depth $y$ from the top and the other is a circular hole of radius $R$ at a depth $4y$ from the top. When the tank is completely filled with water,the quantities of water flowing out per second from both holes are the same. Then,$R$ is equal to

$A$ ball is projected with velocity $V_0$ at an angle of elevation $30^\circ$. Mark the correct statement.