Synthetic detergents are sodium salt of long chain sulphonic acid or alkyl hydrogen sulphate. Hardness in water is due to presence of chlorides, sulphates and nitrates salts of calcium and magnesium. Now detergents are capable of forming soluble salts even with the calcium and magnesium ions present in hard water and forms lather easily in hard water.

Barium and Strontium are alkaline earth metals. They are quite reactive in nature, they do not occur in free state. Strontium is a relatively abundant element in the Earth’s crust. The most common minerals containing strontium are celestine and strontianite. Celestine contains primarily strontium sulfate (SrSO₄), while strontianite contains mostly strontium carbonate (SrCO₃). The most common naturally occurring minerals containing barium are the very insoluble barium sulfate, BaSO₄ (barite), and barium carbonate, BaCO₃ (witherite).

A trend of decreasing electron affinity going down the groups in the periodic table would be expected. The additional electron will be entering in an orbital farther away from the nucleus, and thus would experience a lesser effective nuclear charge. It is fairly obvious that the atoms get bigger as you go down group with the increase in atomic number. The reason is equally obvious – you are adding extra layers of electrons.

Coal based thermal power plants contribute to acid rain because SO₂ and NO₂ are emitted from these plants which form H₂SO₄ and HNO₃ in atmosphere, that cause acid rain. Oxides of carbon are emitted when coal burns, but it does not contribute to acid rain.

Baking soda is a great as a fire extinguisher for electrical fires and grease fires. When baking soda is heated it releases carbon dioxide and produces water.
2NaHCO₃ ⟶ H₂O + CO₂ + Na₂CO₃
Since carbon dioxide is heavier than air and does not support combustion like oxygen does, it smothers the fire while water that is formed cools the fire to below ignition temperature.
Calcium oxide, chemical compound, CaO is also called lime, quicklime, or caustic lime. Calcium oxide is widely used in making porcelain and glass.
Plaster of Paris is a type of building material based on calcium sulphate hemihydrate nominally CaSO₄.1/2H₂O. It is created by heating gypsum to about 300°F (150ºC).
2CaSO₄.2H₂O ⟶ 2CaSO₄.1/2H₂O + 3H₂O (released as steam)

Creating firework colors is a complex endeavor, requiring considerable art and application of physical science. Strontium and barium both are alkaline earth metal and are extremely reactive. They both impart characteristic color to flame. Strontium salts impart a red color to fireworks. Strontium compounds are also important for stabilizing fireworks mixtures. Barium is used to create green colors in fireworks, and it can also help stabilize other volatile elements.

Caffeine also spelled caffei is most commonly consumed by humans in infusions extracted from the bean of the coffee plant and the leaves of the tea bush, as well as from various foods and drinks containing products derived from the kola nut. Acids are added to soft drinks for extra bite and mouth feel. The primary acid used in colas is phosphoric acid, while the one used in citrus flavoured drinks is usually citric acid. Citric acid is a good substitution of ascorbic acid as per nutritional value.

Solder is a fusible metal alloy with a melting point or melting range of 90 to 450 degree Celsius (190 to 840°F), used in a process called soldering where it is melted to join metallic surfaces. It is especially useful in electronics and plumbing. Solder is an alloy of lead and tin.

Philosopher’s wool is a oxide of zinc a white powder used as a pigment, cosmetics, glass, inks and in zinc ointment.

German silver has a color resembling silver, but is an alloy of primarily copper, nickel and zinc. Chlorargyrite is the mineral form of silver chloride (AgCl). It is also known as horn silver. Proustite is a sulfosalt mineral consisting of silver sulfarsenide, Ag₃AsS₃, known also as light red silver or ruby silver ore, and an important source of the metal. Silver nitrate is an inorganic compound with chemical formula AgNO₃. It was once called lunar caustic because silver was called luna by the ancient alchemists.

Rubies and Sapphires are scientifically the same stone, differing only in color. Corundum, the predominating mineral of both, is composed of nearly pure alumina (Al₂O₃).The coloring substance which differentiates rubies and sapphires is believed to be chromium.

Xenon is called the ‘stranger’ gas. This gas very un-reactive and heavier than air, that was why named strange (in greek it means ‘xenon’).

The lightest metal in the periodic table is lithium (Li) with atomic number 3 density 0.53 kg/L. Lithium metal is extremely soft (and highly reactive) and so is unusable for many applications. Osmium is a hard metallic element which has the greatest density of all known elements. It is twice as heavy as lead, and has a specific gravity of 22.59.

Smelting units and paints are the source of the lead poisoning.

The burning of fossil fuel can create another atmospheric pollution problem known as Photo-chemical Smog. Photochemical smog is a condition that develops when primary pollutants like oxides of nitrogen, Volatile organic compounds created from fossil fuel combustion interact under the influence of sunlight to produce secondary pollutants. The major chemical pollutants in Photochemical smog are NO and NO₂, VOCs(volatile organic compounds), Ozone(O₃) and PAN (Peroxyacetyl Nitrate). NO₂ decreases visibility due to yellowish colour. It also contributes to heart and lung problem. Ozone(O₃) contributes to bronchial constriction, coughing and wheezing. PAN causes eye irritation, high toxicity to plants.

Chemical changes occur when a substance combines with another to form a new substance. Crystallization of sodium chloride is not a chemical as water of crystallization can be lost to get salt again. Similarly melting of ice is reversible. However souring of milk is a chemical change as it is not reversible and a new compound is formed.

Polycarbonates are the polymer widely used in making bullet proof material. Bullet proof glass is made by layering a polycarbonate material between pieces of ordinary glass in a process called lamination. A bullet fired will pierce the outside layer of the glass, but the layered polycarbonate glass material is able to absorb the bullet’s energy and stop it. Polycarbonate panels are used for covering advertising posters, construction of office buildings for sound proofing and polycarbonate is also used for making bullet proof jackets.

Methyl alcohol is very dangerous. May be fatal or cause blindness if swallowed. Harmful, if inhaled or absorbed through skin. It cannot be made non poisonous. Some other harmful effects are results into irritation of skin, eyes and respiratory track. It can also effects central nervous system and liver.

Allicin is an oily, yellow liquid, which gives garlic its characteristic odour which is due to the R–S(O)–S–R group. It also has a range of medical properties.