In a perfectly inelastic collision,what happens to the two colliding particles after the collision?

$A$ bullet hits and gets embedded in a solid block resting on a horizontal frictionless table. What is conserved?

Two identical blocks of ice move in opposite directions with equal speed and collide with each other. What will be the minimum speed required to make both the blocks melt completely,if the initial temperatures of the blocks were $-8^{\circ} C$ each (in $ms^{-1}$)? (Specific heat of ice is $2100 \ Jkg^{-1} K^{-1}$ and latent heat of fusion of ice is $3.36 \times 10^{5} \ Jkg^{-1}$)

When does the total kinetic energy of two bodies moving in opposite directions become zero after a collision?

$A$ neutron having a mass of $1.67 \times 10^{-27} \ kg$ and moving at $10^8 \ m/s$ collides with a deuteron at rest and sticks to it. If the mass of the deuteron is $3.34 \times 10^{-27} \ kg$,then the speed of the combination is:

$A$ ball is dropped from a height of $10 \,m$. The ball embeds itself $1 \,m$ into the sand and stops. Which of the following statements is correct regarding this process?