Which type of forces are responsible for the explosion of a chemical bomb: internal or external forces?

$A$ particle is acted upon by a force whose components' variations with time are shown in the diagrams. The magnitude of the change in momentum of the particle in $0.1\,s$ is:

Two trains $A$ and $B$ are running in the same direction on parallel rails such that $A$ is faster than $B$. Packets of equal weight are transferred between them. What will happen due to this?

$A$ player kicks a football of mass $0.5 \ kg$ and the football begins to move with a velocity of $10 \ m/s$. If the contact between the leg and the football lasts for $\frac{1}{50} \ s$,then the force acted on the football should be .......... $N$.

$A$ ball of mass $150 \, g$ moving with a velocity of $12 \, m/s$ hits a bat and returns with a velocity of $20 \, m/s$ in the opposite direction within $0.01 \, s$. The force exerted by the bat on the ball is ........... $N$.

The $F-t$ graph for an object is shown in the figure. What will be the magnitude of the change in momentum $(\Delta p)$ in the interval of $0.03\, s$ from the start?