Which of the following is not an example of a perfectly inelastic collision?

$A$ neutron of mass $1.67 \times 10^{-27} \ kg$ moving with a velocity of $10^8 \ m/s$ collides with a deuteron at rest and sticks to it. If the mass of the deuteron is $3.34 \times 10^{-27} \ kg$,what will be the velocity of the combined system?

$A$ body of mass $m$ moving with speed $3 \ m/s$ collides with a body of mass $2m$ at rest. The coalesced mass will start to move with a speed of (in $m/s$)

Ball $A$ of mass $1 \,kg$ moving along a straight line with a velocity of $4 \,ms^{-1}$ hits another ball $B$ of mass $3 \,kg$ which is at rest. After collision, they stick together and move with the same velocity along the same straight line. If the time of impact of the collision is $0.1 \,s$, then the force exerted on $B$ is (in $\,N$)

$A$ $50\, g$ bullet moving with velocity $10\, m/s$ strikes a block of mass $950 \,g$ at rest and gets embedded in it. The loss in kinetic energy will be ............... $\%$

$A$ particle of mass $m$ moving with velocity $v$ collides with a stationary particle of mass $2m$. After collision,they stick together and continue to move together with velocity ........