Metals And Non Metals

Concept: Chemical symbols are one- or two-letter abbreviations for chemical elements. Many symbols are derived from the element's English name, but some come from their Latin or Greek names. Step 1: Recall the symbol for Silver The chemical symbol for silver is Ag. This symbol is derived from its Latin name, argentum. Step 2: Analyze the options and identify other elements
(1) Ag: This is the chemical symbol for Silver (from Latin: argentum). Correct.
(2) Au: This is the chemical symbol for Gold (from Latin: aurum).
(3) Al: This is the chemical symbol for Aluminium (or Aluminum).
(4) Ar: This is the chemical symbol for Argon, a noble gas. Therefore, the symbol for silver is Ag.

Concept: Iron is commercially produced in several forms, which differ mainly in their carbon content and the presence of other impurities. Purity refers to the percentage of iron, with lower carbon and impurity content indicating higher purity. Step 1: Understanding different forms of commercial Iron (e) Pig Iron: This is the crude iron obtained directly from a blast furnace. It has a high carbon content, typically 3.5% to 4.5%, and also contains other impurities like silicon, manganese, phosphorus, and sulfur. It is very brittle and not very useful directly for most applications. (f) Cast Iron: Produced by re-melting pig iron, often with scrap iron and steel, and then casting it into molds. The carbon content is typically 2% to 4%. It is hard and brittle but has good fluidity for casting. Impurities are still present. (g) Wrought Iron: This is historically the purest form of commercial iron. It has a very low carbon content, usually less than 0.08% (often around 0.02-0.03%), and very few other impurities. It is tough, malleable, and ductile, but softer than steel. It contains some slag (fibrous inclusions of iron silicate), which gives it a characteristic grain. (h) Steel: Steel is an alloy of iron and carbon, typically with a carbon content between 0.2% and 2.1% by weight. The properties of steel can be varied widely by changing the carbon content and adding other alloying elements (like manganese, chromium, vanadium, tungsten). Steel is generally stronger and more versatile than cast iron or wrought iron. Step 2: Comparing Carbon Content (as an indicator of purity) (i) Pig Iron: C (Least pure) (j) Cast Iron: C (k) Steel: C (l) Wrought Iron: C (Most pure commercial form) Step 3: Identifying the most pure form Based on the low carbon content and fewer impurities, Wrought Iron is considered the most pure form of commercial iron among the options.

Concept: Galvanization is a process of applying a protective coating to iron or steel to prevent rusting (corrosion). Step 1: Understanding Galvanization Rusting is the corrosion of iron due to its reaction with oxygen and moisture in the atmosphere, forming hydrated iron(III) oxide. Galvanization is a common method to protect iron from rusting. The process involves coating the iron or steel with a layer of another metal. Step 2: The Metal Used in Galvanization The metal most commonly used for galvanizing iron is Zinc (Zn). The process typically involves dipping the iron or steel object into molten zinc (hot-dip galvanizing) or using electroplating to deposit a zinc layer. Step 3: How Zinc Protects Iron Zinc protects iron in two main ways: \begin{enumerate} % Option („) Barrier Protection: The zinc coating forms a physical barrier that prevents oxygen and water from reaching the iron surface. % Option (…) Sacrificial Protection (Cathodic Protection): Zinc is more reactive than iron (it is higher in the electrochemical series). If the zinc coating is scratched or broken and the iron is exposed, the zinc will corrode preferentially (acts as a sacrificial anode) instead of the iron. The zinc "sacrifices" itself to protect the iron. Step 4: Analyzing the options
(1) Sn (Tin): Coating iron with tin is called "tinning" (e.g., tin cans). Tin protects iron mainly by barrier protection. If the tin coating is scratched, the iron underneath can rust rapidly because iron is more reactive than tin (tin provides cathodic protection to iron only in certain environments, but generally, iron is anodic to tin).
(2) Ni (Nickel): Nickel plating can also protect iron, usually by electroplating.
(3) Cu (Copper): Copper plating can be used, but copper is less reactive than iron. If the copper coating is scratched, the iron will corrode.
(4) Zn (Zinc): This is the metal used for galvanization, providing both barrier and sacrificial protection. Therefore, galvanized iron sheets are coated with zinc.

Concept: The Earth's crust is composed of various elements, but some are significantly more abundant than others by mass. Step 1: Major Elements in Earth's Crust by Approximate Percentage Mass % Option (A) Oxygen (O): About 46.6% % Option (B) Silicon (Si): About 27.7% % Option (C) Aluminum (Al): About 8.1% % Option (D) Iron (Fe): About 5.0% % Option (E) Calcium (Ca): About 3.6% % Option (F) Sodium (Na): About 2.8% % Option (G) Potassium (K): About 2.6% % Option (H) Magnesium (Mg): About 2.1% All other elements make up the remaining percentage (less than 2%). Step 2: Identifying the most abundant element From the list, Oxygen (O) is the most abundant element in the Earth's crust by mass. It is primarily found in combined form in silicate minerals (like quartz, feldspar, mica), oxides, carbonates, sulfates, etc. Step 3: Evaluating the options % Option (I) (1) O (Oxygen): - Most abundant. % Option (J) (2) Cl (Chlorine): Much less abundant than oxygen or silicon. Found in minerals like halite (NaCl). % Option (K) (3) Si (Silicon): - Second most abundant. % Option (L) (4) S (Sulfur): Less abundant than oxygen or silicon. Found in sulfide and sulfate minerals. Therefore, Oxygen is the most abundant element in the Earth's crust.

Concept: Haemoglobin (often spelled Hemoglobin) is a protein in red blood cells responsible for transporting oxygen in the blood of vertebrates and some invertebrates. Its structure includes a metal ion. Step 1: Structure and Function of Haemoglobin Haemoglobin is a complex protein containing a non-protein component called haem (or heme). Each haem group contains a central metal atom. This metal atom is crucial for the oxygen-binding capacity of haemoglobin. The primary function of haemoglobin is to bind to oxygen in the lungs (or gills) and transport it to the tissues throughout the body, where it releases the oxygen. Step 2: The Metal in Haemoglobin The metal atom at the center of each haem group in haemoglobin is Iron (Fe). Specifically, it is an iron(II) ion, . Each haemoglobin molecule typically has four haem groups, and thus can bind up to four oxygen molecules. The binding of oxygen to the iron atom is what gives oxygenated blood its bright red color, while deoxygenated blood is a darker red/purplish. Step 3: Analyzing the options % Option (Q) (1) Fe (Iron): Correct. Iron is the central metal atom in the haem group of haemoglobin. % Option (R) (2) Co (Cobalt): Cobalt is the central metal atom in Vitamin B12 (cobalamin), but not in haemoglobin. % Option (S) (3) Mg (Magnesium): Magnesium is the central metal atom in chlorophyll, the pigment responsible for photosynthesis in plants, but not in haemoglobin. % Option (T) (4) Na (Sodium): Sodium is an important electrolyte in the body (as ions) involved in nerve function and fluid balance, but it is not the metal in haemoglobin. Therefore, the metal in haemoglobin is Iron (Fe).

Concept: Sodium (Na) is a highly reactive alkali metal. Its storage method must prevent it from reacting with components of the air or other common substances. Step 1: Reactivity of Sodium Sodium is very reactive. It readily reacts with: % Option ({) Oxygen in the air: It tarnishes rapidly in air, forming sodium oxide ( ) and if moisture is present, sodium hydroxide (NaOH). % Option (|) Moisture (water vapor) in the air: It reacts with water to form sodium hydroxide and hydrogen gas. This reaction is exothermic (produces heat). Step 2: Analyzing storage options % Option (}) (1) Water: Sodium reacts vigorously, even explosively, with water. So, it cannot be stored under water. The heat generated can ignite the hydrogen gas produced. % Option (~) (2) Kerosene Oil: Kerosene is a hydrocarbon oil. Sodium does not react with kerosene. Kerosene also prevents sodium from coming into contact with air (oxygen and moisture). Therefore, sodium is commonly stored under kerosene oil or other similar inert mineral oils. % Option () (3) Alcohol (e.g., Ethanol ): Sodium reacts with alcohols (which have an -OH group) to produce sodium alkoxides and hydrogen gas, although the reaction is generally less vigorous than with water. So, alcohol is not suitable for storing sodium. % Option (€) (4) Hydrogen: Storing a reactive metal under a gas is generally not practical for preventing surface reactions with air unless it's a completely sealed, inert atmosphere of pure hydrogen, which is not how it's "usually stored". Also, sodium can form sodium hydride ( ) with hydrogen under certain conditions (e.g., heating). Step 3: Identifying the usual storage method Due to its high reactivity with air and water, sodium metal is usually stored under an inert liquid like kerosene oil to protect it from oxidation and reaction with moisture.

Step 1: Understand the reactivity of metals.
Some metals are highly reactive and readily react with air (oxygen and moisture) and water. To prevent these reactions and ensure their safe storage, they are often stored under a protective layer of a substance that prevents contact with air and moisture. Step 2: Evaluate the reactivity of the given metals.
Sodium (Na) and Potassium (K): These are alkali metals, located in Group 1 of the periodic table. They are extremely reactive metals. They react vigorously with oxygen in the air (even at room temperature, causing them to tarnish rapidly) and violently with water, releasing hydrogen gas which can ignite due to the heat generated. Therefore, they need to be stored in an inert medium.
Zinc (Zn): Zinc is a moderately reactive metal. It reacts with oxygen in the air to form a protective layer of zinc oxide, which prevents further corrosion. It does not react vigorously with water at room temperature.
Copper (Cu): Copper is a relatively unreactive metal. It slowly reacts with atmospheric gases over time to form a greenish patina (copper carbonate), but it does not react with water or oxygen rapidly at room temperature.
Iron (Fe): Iron is a moderately reactive metal. It reacts with oxygen and moisture in the air to form rust (hydrated iron(III) oxide), but this process is slow and does not require storage in kerosene. Step 3: Determine the appropriate storage method.
Kerosene is an organic solvent and does not react with highly reactive metals like sodium and potassium. It acts as a barrier, preventing their contact with air and moisture. Therefore, sodium and potassium are stored in kerosene to prevent their highly exothermic reactions with oxygen and water. $ $