Question

It is necessary to secure an inflated baloon tightly

Answer 1

it is surely necessary to secure an inflated ballon.As You add more gas or inflate the balloon, the pressure inside the ballon increases.So if you will not secure it tightly it may burst.

Answer 2

if an inflated balloon is not held tightly then the balloon full of air goes down slowly (becomes smaller and smaller slowly) And after a while all the air will escaped from the balloon. as it is held tightly