JAMB - Chemistry (2018 - No. 19)
In the shown experiment (Fig. 1) the litmus paper will initially
be bleached
turn green
turn red
turn blue
Explication
\(NH_4Cl → NH_3 + HCl\). rate of diffusion of substances depends too on their molar mass, the smaller the molar mass of a substance the faster the rate of diffusion of that substance. so the litmus paper initially turns blue because ammonia will get to it first since it diffuses faster than HCl.