The types of chemical reactions are combination, decomposition, displacement, double displacement, and redox (oxidation-reduction).

Carbon is a non-metal existing in various allotropes, each with unique properties. Diamond, the hardest known natural substance, boasts exceptionally high melting and boiling points, while graphite, another allotrope, conducts electricity. These differing properties stem from the distinct arrangement of carbon atoms in their respective structures. Carbon's versatility makes it a crucial element, forming the basis of organic chemistry and essential to life itself. Its ability to bond in diverse ways contributes to the vast array of organic compounds found in nature and synthesized by humans.

1. **Carbon's Allotropy:** * *Exists in different forms (allotropes).* 2. **Diamond (allotrope):** * *Hardest natural substance.* * *High melting/boiling point.* 3. **Graphite (allotrope):** * *Conducts electricity.*

Acids are one of the three main categories of chemical compounds (along with bases and salts). They are characterized by several key properties: * **Taste:** Acids have a sour taste. Think of the sourness of lemon juice (citric acid) or vinegar (acetic acid). * **Effect on litmus:** Acids turn blue litmus paper red. Litmus paper is an indicator – a substance that changes color depending on whether a solution is acidic or basic. * **Reactions with metals:** Acids react with many metals, producing hydrogen gas (H₂) as a byproduct. This is a characteristic chemical reaction of acids. * **Reactions with carbonates:** Acids react with carbonates (like calcium carbonate in limestone) to produce carbon dioxide (CO₂) gas, water, and a salt. * **pH scale:** Acids have a pH less than 7 on the pH scale, which measures acidity and basicity. The lower the pH, the stronger the acid. * **Neutralization:** Acids react with bases in a neutralization reaction to form salt and water. Acids are classified as strong or weak based on their degree of ionization (how readily they release hydrogen ions, H⁺, in solution). Strong acids ionize completely, while weak acids only partially ionize. Acids are found in many everyday applications and are vital in various biological processes. Examples include citric acid in fruits, acetic acid in vinegar, and hydrochloric acid in our stomachs (which aids digestion).

* **Essential functions for life maintenance.** * **Includes:** nutrition, respiration, transport, excretion. * **Requires constant molecular movement within cells.** * **Continues even during rest (e.g., breathing, tissue repair).** * **Energy from food is crucial.** * **Depends on continuous energy input and system maintenance.**

Chemical reactions are processes that lead to the transformation of one set of chemical substances to another. This transformation involves the rearrangement of atoms – bonds are broken and new bonds are formed, resulting in different molecules with different properties. A chemical equation is a symbolic representation of a chemical reaction. It uses chemical formulas to show the reactants (the starting substances) and the products (the substances formed) involved in the reaction. For example: H₂ + O₂ → H₂O This equation shows that hydrogen (H₂) reacts with oxygen (O₂) to produce water (H₂O). However, this equation is *unbalanced* because it doesn't show an equal number of atoms of each element on both sides of the arrow. A balanced equation, crucial because of the law of conservation of mass, would be: 2H₂ + O₂ → 2H₂O This balanced equation shows that two molecules of hydrogen react with one molecule of oxygen to produce two molecules of water. The number of hydrogen and oxygen atoms is the same on both sides of the equation. Balancing chemical equations ensures that the law of conservation of mass is obeyed – mass is neither created nor destroyed in a chemical reaction, only rearranged.

Based on the provided text, development is defined as progress that balances economic growth with environmental protection and resource conservation. It's not simply economic growth, but rather a sustainable process that ensures resources are available for future generations by avoiding depletion. The implication is that unsustainable practices, like overuse of groundwater and fossil fuels, hinder true development.

The Indian economy, like most others, is divided into three main sectors: * **Primary Sector:** This sector involves the extraction and production of raw materials. Examples include agriculture (farming, forestry), fishing, and mining. * **Secondary Sector:** This sector focuses on manufacturing and processing of raw materials into finished goods. Examples include industries, construction, and power generation. * **Tertiary Sector (Services Sector):** This sector provides services to individuals and businesses. Examples include banking, finance, insurance, transportation, communication, healthcare, education, and tourism.

1. **Non-metal:** Carbon is a non-metallic element. 2. **Allotropes:** It exists in different forms called allotropes. 3. **Diamond:** *Hardest natural substance,* high melting/boiling point, non-conductor. 4. **Graphite:** *Conducts electricity*. 5. **Varied properties:** Different allotropes exhibit vastly different physical properties.