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. Water pollution is serious problem. . It makes water dirty. . It is caused by waste and chemical. . factories dump dirty water into rivers . oil spills pollute the oceans . clean water is important for life . Dirty water can make us sick . we should not throw trash in water . without water no life is possible. . Everyone must stop water pollution.

Potassium bromide is an ionic compound, which is a type of salt. It is a stable, white solid that dissolves easily in water. It is not a metal and its properties are very different from the elements it is made of. Unlike potassium metal, potassium bromide does not react with air or water. The solid form is odorless, and when it is dissolved in water, it can have a pungent, bitter, and salty taste. found: The compound was prepared by chemists like Antoine Balard in 1826, after he discovered the element bromine. Made: It is formed in an exothermic reaction when solid potassium metal reacts with liquid bromine. 2K(s)+Br_2(l)rightarrow2KBr(s)+heat Uses: It is used as a medicine for veterinary medicine to treat seizures in dogs. It was also used in human medicine in the past. • It contains the elements potassium (K) and bromine (Br). Potassium is in Group 1, an alkali metal. Bromine is in Group 17, a halogen. The SECRET ingredient that is making Americans SICK

Definition :Opportunity cost is the value of the next best option you give up when you make a decision. It is not always about money – it can also be about time, enjoyment, or any other benefit you miss out on. Why it is important: • Resources like time, money, and energy are limited. • Because of scarcity, people, businesses, and governments must make choices. • Understanding opportunity cost helps us make smarter decisions. Everyday Life Examples: 1. Students If a student spends the evening revising for exams, the opportunity cost may be watching their favorite TV show or hanging out with friends. 2. Workers If a worker chooses to work overtime, the opportunity cost is the family time or rest they give up. 3. Consumers If you buy a new football, the opportunity cost might be the snacks, clothes, or video games you could have bought instead. 4. Producers (Firms)If a company uses land to build a factory, the opportunity cost might be using that land to build houses or a shopping mall. 5. Governments If the government spends money on building new roads, the opportunity cost could be fewer funds for hospitals or schools. Football Example: If you spend your evening playing football, the opportunity cost could be: • Time spent studying and improving grades. • Playing video games with friends. • Doing another sport or hobby. Key Point: Every decision involves giving up something. Opportunity cost reminds us to think: “If I choose this, what am I missing out on?”