Which of the following changes is observed when we move across the row from left to right in the periodic table? Atomic radius increases

Atomic radius decreases

Number of protons decreases

Chemical reactivity of metals increases

c

explanation:

answer;

18.5 seconds

explanation;

velocity is distance covered per unit time; it is given by displacement divided by time.

thus; time = displacement/velocity

total time = total displacement/velocity

total distance = 5000 meters south

total time = 5000/4.5

                  = 1111.11 seconds

but; 1 minute = 60 sec

thus; 1111.11 /60

                = 18.51 seconds

thus; the time taken is 18.5 seconds