I always advise people never to give advice.

Anomalous Expansion of Water
The way substances generally react to heat is that they expand when heated as the density decreases and vice versa takes place then they are cooled. This is not the case with water. The general tendency of cold water remains unchanged until 4oC. The density of water gradually increases as you cool it. When you reach 4oC, its density reaches a maximum. When you cool water further to make ice (i.e. 0oC), it expands with a further drop in temperature; meaning the density of water decrease when you cool it form 4oC to 0oC.

The effect of this expansion of water is that the coldest water is always present on the surface which is why ice is seen on the surface of water. Since water at 4oC is the heavest, this water settles on the bottom of the water body and the lightest i.e. the coldest layer accumulates on the top layer. This is why the top of the water is always the first to freeze. Since ice and water are both bad conductors of heat, this top layer of ice insulates the rest of the water body from the cold thereby protecting all the life in the water body.

Introduction
Expansion means an increase in the size of an object. Most solids and liquids expand when heated and contract when cooled. When heat is provided to a body, its particles gets hot and vibrate with greater amplitude; space between particles becomes more prominent. This increase in amplitude causes an increase in the body’s length; this is called thermal expansion.

According to the kinetic molecular theory, when an object is heated, the molecules acquire more kinetic energies which enables them to overcome their intermolecular forces. Therefore, the vibrations of the molecules increase and their displacements about their mean positions increase. As a result of this, the average distance between the molecules of the substance becomes larger reading an increase in the size of the substance. This increase in the dimension of the heated object depends on the strength of the intermolecular forces. If their forces are stronger, the expansion will be small and vice versa.

The intermolecular forces are stronger in solids than in liquids and weakest in gases. Hence, when heat is applied, gases expand more than liquids and liquids expand more than solids. Each particular substance has an intermolecular force peculiar to it. Therefore, the addition of heat causes different expansions in different substances.

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Electroscopej
An electroscope is a device used to detect the presence of an electric charge on a body. It is known as a charge-detecting device. An electroscope is made up of a metal detector knob on which it is connected to a pair of metal leaves hanging from the bottom of the connecting rod. It responds to the presence of a charge through the movement of electrons either into or away from the leaves. In both cases, the leaves separate. When no charge is present, the metal leaves hang loosely downward. When an object with a charge is brought near an electroscope, either of these two things occur.

1. When the charge is negative, the electrons in the metal of the electroscope repels and move toward the leaves on the bottom. This causes the leaves to gain temporary negative charge and because like charges repel, the leaves separate again. When the charge is removed, the electrons return to their original position and the leaves relax.

2. When the charge is positive, electrons in the metal of the electroscope are attracted to the charge and move upward out of the leaves. This results in the leaves having a temporary positive charge and because like charges repel, the leaves separate. When the charge is removed, the electrons return to their original position and