No. Singapore does not have volcanoes. As a matter of fact, it can. When Krakatau erupted, Singapore WAS affected. Search Google and see for yourself. Although, SIngapore CANNOT be affected most of...
With a population of about 4,987,600 people excluding tourist in a small area of 710.2 km2 it is known to be the third most densely populated country. It's really not that crammed as long as you know...