A1 How many empty plastic bottles weighing $50 \mathrm{~g}$ do we need to collect if we want one ton of plastic bottles?
(A) 200
(B) 2000
(C) 20000
(D) 200000
(E) 2000000
A1. It is necessary to collect 20000 plastic bottles, since $1 \mathrm{t}=1000000 \mathrm{~g}=20000 \cdot 50 \mathrm{~g}$.