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

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 $3.36 \times 10^{5} \ Jkg^{-1}$)

$A$ body of mass $20 \ kg$ moving with a velocity of $10 \ m/s$ collides with a stationary body of mass $5 \ kg$ and sticks to it. The combined kinetic energy of the system after the collision is . . . . . . $J$.

$A$ completely inelastic collision is one in which the two colliding particles

$A$ 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?

$A$ body of mass $5 \times 10^{3} \, kg$ moving with speed $2 \, m/s$ collides with a body of mass $15 \times 10^{3} \, kg$ inelastically and sticks to it. The loss in $K.E.$ of the system will be (in $kJ$):