Question $1$

An ink droplet has been placed in a fluid at time $t=0$ at $T=300K,$ it spreads to a disk of diameter of $10$

$cm$ at time $t=5s,$ what is the diameter of the spreading disk at time $t=10s?$ When is expected for the

diameter to increases to $15cm?$

Question $2$

The same measurement, now the concentration at different radical at time $t=5s.$ What is the diffusion

coefficient $($dm$2/$s$)?$