Questions

The Gulf of Mexico is the largest among all the gulfs in the world.

A gulf is nothing but a large inlet from the ocean into the landmass, typically with a narrower opening than a bay.

The Gulf of Mexico is an ocean basin mostly surrounded by the North American continent. It is a unique, semi-enclosed sea located between the Yucatan and Florida peninsulas, at the southeast shores of the United States.

The given puzzle follows a pattern that,

Number - <last digit> <sum of all digits>.

111 - 13

112 - 24

113 - 35

So 

117 - 79

When the piece of iron is lowered into the water, the water level in the bucket increases. And so the pressure at the bottom of bucket also increases. Thus the total thrust at the botto also increases. Therefore the spring balance reading increases.