Tooth enamel is one of the four major tissues that make up the tooth in humans and many other animals. It makes up the visible part of the tooth covering the crown. The other major tissues are dentin, cementum and dental pulp. It protects the teeth but can be easily decayed and destroyed. It is the hardest substance in the human body and contains the highest percentage of minerals 96% . This mineral is hydroxyapetite which is crystalline calcium phosphate. In humans enamel varies in thickness over the surface of the tooth thickest at the cusps and thinnest at the border.
$${ Ca }_{ 10 }{ (PO }_{ 4 })_{ 6 }{ (OH) }_{ 2 }\left( s \right) +8{ H }^{ + }\left( aq \right) \rightarrow 10{ Ca }^{ 2+ }\left( aq \right) +6{ HPO }_{ 4 }^{ 2- }\left( aq \right) +2{ H }_{ 2 }O\left( l \right)$$

Potassium, Nitrogen, and Phosphorous are normally derived from the soil in the form of inorganic salts and are nutrients available in fertilizers that make up 0.5 to 6.0 percent. Hence iron is a nutrient that is not available in fertilizers.

Silver is a soft metal with high thermal and electrical conductivity. It is malleable and ductile similar to gold. However, silver content in ores mines in India is about 1% obtained as a by-product in the mining of gold and lead. Thus, silver is highly expensive to be drawn into wires for the industries.

Aqua regia is a chemical solution that is obtained by mixing one part nitric acid and three parts hydrochloric acid. It can dissolve gold, platinum, titanium, and other noble metals.

Mercury is a metal which is liquid at room temperature.

Sodium is so soft that it can be cut with a knife. It reacts vigorously with oxygen when kept open in the air and hence, we keep it immersed in kerosene oil. It also reacts vigorously with water.

Malleability is the property by which a substance can be converted into sheets by beating with a hammer.
   $$\bullet$$ Iron, aluminum, and copper are metals and therefore are malleable.
   $$\bullet$$ Carbon is a nonmetal and is neither malleable nor ductile.
Coal is a form of carbon and is non-metal. If it is beaten by a hammer, it will break into pieces.

When a piece of magnesium ribbon is ignited, light and heat are produced.

The oxides of metal are basic in nature or in other words they react with acids to form salt and water. In the case of non-metals, they are acidic in nature and form acids when they dissolve in water.

Fe displaces the Cu from $$CuSO_{4}$$ solution in beaker A as Fe is more reactive than Cu. 

Non-metals which are present in fertilizers and enhance the growth of plants are nitrogen and phosphorus. Potassium is a metal. It is also present in fertilizers.

Sulfur is a non-metal and its property is consistent with that of other non-metals, that's why it does not conduct electricity.

The properties of non-metals are:

A student added zinc granules to copper sulphate solution taken in a test tube. The correct observations made by the student will be:
(A) zinc granules have no regular shape.
(B) zinc granules are silvery-grey colored.
(C) colour of zinc granules changed to brownish-black due to chemical change.
(D) $$\displaystyle CuSO_4$$ change into $$\displaystyle ZnSO_4 $$ due to the following chemical change.

$$\displaystyle CuSO_4 + Zn \rightarrow ZnSO_4+Cu \downarrow$$

Unlike metals which have a  'sea' of free electrons that can be used to conduct electricity, Sulphur is an insulator.

Copper and iron being metals conduct electricity due to the presence of free electrons.

Graphite conducts electricity due to the motion of non bonded electrons between its adjacent layers.

Non metallic oxide dissolves in water to form an acid.

The ability to be hammered, pressed, or rolled into thin sheets without breaking is called malleability. Metals are generally malleable.

Sodium and magnesium metal react with the oxygen of the air at room temperature to form sodium oxide and magnesium oxide respectively. These oxides react with water to form hydroxides.

Oxide of sodium is strongly basic due to the presence of  $$O^{-2}$$ which is a strong base with high tendency to combine with hydrogen ion.

Gallium is liquid at ordinary temperature.

A sonorous alloy is bell metal.
Bell metal (copper, tin)
Type metal (lead, tin, antimony)
Duralumin (copper, aluminum)

The metals, which are low in the reactive series, undergo  reduction reaction. Their metal oxides react with carbon to reduce the metal oxide to its metal and form an oxide of carbon.

$$2CuO+C \rightarrow 2Cu+CO_2$$

Metals are generally sonorous, and good conductors of heat and electricity. On the other hand, most non-metals are not sonorous and are bad conductors of heat and electricity.

Metals have free electrons which can conduct heat and electricity, So, metals are good conductor of heat and electricity.