If a racquet ball is one long strand of molecules, if you made a cut in the ball, wouldn't the whole ball fall apart?

A racquet ball is made of vulcanized rubber. Rubber consists of countless molecules, each one of which is principally a long chain of carbon atoms, decorated with hydrogen and other atoms. It resembles of bowl of tiny spaghetti strands though each rubber molecule is much, much longer than it is thick. But simple rubber melts rather easily and becomes gooey when warm. To make it more durable, it must be vulcanized. During vulcanization, the individual rubber molecules are cross-linked to form a permanent network of coupled strands. They can't move relative to one another, which is why the racquet ball can't melt. It can only burn when you heat it. So the whole racquet ball is one giant molecule. If you cut it in half, you are slicing the molecule in half. It doesn't crumble, it just has many of its bonds broken. That's not a problem because bonds break and remake all the time in the molecules around us.

Why doesn't glass have electrons to carry heat. What is glass made of?

Like everything in our world, glass does have electrons. Its atoms are built out of electrons. But those electrons are localized on the individual atoms or between them in such as way that they can't move easily. When you try to push these electrons through the glass, they won't go. Thus neither heat nor electricity flow easily through glass. In a metal, some of the electrons are mobile and can carry heat and electricity.

What is fire?

The fire of a burning candle begins with vaporized wax. Heat from the flame melts wax, which then flows up the wick because of its attraction to the fibers. The wax then becomes so hot that it turns into a gas and this gas mixes with air at the bottom of the flame. When the temperature becomes high enough, the wax molecules begin to decompose into fragments that react chemically with oxygen molecules. Water and carbon dioxide molecules are produced in the reaction and chemical potential energy is released as thermal energy. This thermal energy provides the candle's light and also the heat needed to sustain the combustion. The glow that the candle emits comes primarily from hot particles of carbon in the flame. These particles emit thermal radiation with a color spectrum that is characteristic of the flame's temperature.