If the unit of length and force be increased four times,then the unit of energy is

$A$ hydride of nitrogen which is acidic is

The osmotic pressure of a $5\% \, w/v$ solution of cane sugar at $150 \, ^\circ C$ is ......... $atm$.

Two ions of masses $4 \ amu$ and $16 \ amu$ have charges $+2 e$ and $+3 e$ respectively. These ions pass through a region of constant perpendicular magnetic field. If the kinetic energy of both ions is the same,then:

Four particles $A, B, C$ and $D$ of equal mass $m$ are placed at the four corners of a square. They move with equal uniform speed $v$ towards the intersection of the diagonals. After the collision,particle $A$ comes to rest,particle $B$ traces its path back with the same speed $v$,and particles $C$ and $D$ move with equal speeds $v'$. What is the velocity of particle $C$ after the collision?

If $A+2 B=\begin{bmatrix} 1 & 2 & 0 \\ 6 & -3 & 3 \\ -5 & 3 & 1 \end{bmatrix}$ and $2 A-B=\begin{bmatrix} 2 & -1 & 5 \\ 2 & -1 & 6 \\ 0 & 1 & 2 \end{bmatrix}$,then $\operatorname{Tr}(A)-\operatorname{Tr}(B) = $