Sound and Light
What is sound measured by?
Decibels (dB)
What are the key properties of noble gases in Group 0?
Noble gases are colorless, odorless, and inert (unreactive) due to having a full outer electron shell. They have low melting and boiling points and exist as gases at room temperature. They are used in applications like lighting (neon lights) and balloons (helium).
What is the process of digestion?
Digestion is the process by which the body breaks down food into smaller molecules that can be absorbed and used for energy, growth, and repair. It involves both mechanical (chewing, churning) and chemical (enzymatic) processes. Digestion occurs in the digestive system, which includes the mouth, stomach, small intestine, and large intestine.
What is a chemical reaction?
A chemical reaction is a process in which one or more substances (reactants) are transformed into new substances (products). During the reaction, bonds between atoms are broken and formed.
What are the key factors that affect a person’s health?
Diet: Eating a balanced diet with the right nutrients.
Exercise: Regular physical activity to maintain fitness.
Sleep: Getting enough quality sleep.
Mental Health: Managing stress and emotional well-being.
Environment: Clean air, safe water, and a safe living environment.
Genetics: Inherited traits that affect health.
What is the speed of light?
The speed of light is about 300,000 kilometers per second (km/s) in a vacuum.
Why do alkali metals become more reactive as you go down Group 1?
As you move down Group 1, the atoms become larger, and the outer electron is further from the nucleus. This means it is less strongly attracted to the nucleus and more easily lost, making the metals more reactive.
How does the stomach help with digestion?
The stomach mechanically churns food and mixes it with gastric juices containing acid and the enzyme pepsin to break down proteins. The acid also helps kill harmful bacteria in the food.
What are the signs of a chemical reaction?
Some common signs of a chemical reaction include:
Color change
Gas formation (bubbles)
Temperature change (heat released or absorbed)
Precipitate formation (a solid forms in a liquid)
Why is a balanced diet important for good health?
A balanced diet provides the body with the nutrients it needs to function properly. It includes the right amounts of carbohydrates, proteins, fats, vitamins, minerals, and water. A balanced diet helps to maintain energy levels, support growth, repair body tissues, and boost the immune system.
What is the difference between high-pitched and low-pitched sounds?
High-pitched sounds have shorter wavelengths and higher frequencies (like a whistle), while low-pitched sounds have longer wavelengths and lower frequencies (like a drum)
What are the main properties of alkali metals in Group 1?
Alkali metals are highly reactive with water, form alkaline hydroxides when they react with water, and have low melting points. They are soft and can be cut easily with a knife. As you go down the group, their reactivity increases.
What is the role of enzymes in digestion?
Enzymes are biological catalysts that speed up chemical reactions. In digestion, enzymes break down large, complex molecules like carbohydrates, proteins, and fats into smaller molecules that can be absorbed. For example, amylase breaks down starches, protease breaks down proteins, and lipase breaks down fats.
What are exothermic and endothermic reactions?
Exothermic reactions release energy, usually in the form of heat (e.g., combustion of wood).
Endothermic reactions absorb energy from their surroundings, causing a temperature decrease (e.g., dissolving ammonium nitrate in water).
What are the different types of nutrients, and why are they important?
Carbohydrates: Provide energy. Found in foods like bread, rice, and pasta.
Proteins: Important for growth and repair of tissues. Found in meat, beans, and nuts.
Fats: Provide long-term energy and help with the absorption of vitamins. Found in oils, butter, and fatty fish.
Vitamins and Minerals: Help maintain various body functions, including the immune system and bone health. Found in fruits, vegetables, and dairy.
Water: Keeps the body hydrated and helps regulate body temperature.
What is refraction, and how does it affect the appearance of objects in water?
Refraction is the bending of light as it passes from one medium to another (like air to water). When light enters water, it slows down and changes direction, making objects appear shifted or distorted from their actual position.
What are the characteristics of halogens in Group 7?
Halogens are non-metals and are highly reactive, especially with alkali metals. They form salts when they react with metals, and they have low melting and boiling points. They exist as diatomic molecules (e.g., Cl₂) and are often gases or liquids at room temperature
How are nutrients absorbed in the small intestine?
The small intestine has tiny finger-like projections called villi that increase the surface area for absorption. Nutrients like glucose, amino acids, and fatty acids pass through the walls of the small intestine and into the bloodstream.
What is the role of activation energy in a chemical reaction?
Activation energy is the minimum energy required to start a chemical reaction. It helps break the bonds of reactants so that they can rearrange and form new products. Even exothermic reactions need activation energy to begin.
How does physical activity benefit health?
Improves cardiovascular health (heart and blood vessels).
Strengthens muscles and bones.
Boosts mental health by reducing stress and anxiety.
Helps maintain a healthy weight and metabolism.
Improves sleep quality.
Reduces the risk of chronic diseases like diabetes and heart disease.
Why does sound travel faster in water than in air?
Sound travels faster in water than in air because particles in water are closer together than those in air. The closer the particles are, the faster the sound can transfer its energy through the medium.
How does the reactivity of halogens change as you move down Group 7?
The reactivity of halogens decreases as you move down the group. This is because the outer electrons are further from the nucleus, and it becomes harder for the atom to gain an electron needed to form a stable ion.
What happens in the stomach during digestion?
The stomach is responsible for both mechanical and chemical digestion. The stomach churns food to break it down physically, while gastric juices containing hydrochloric acid and pepsin (a digestive enzyme) break down proteins. The acidic environment also kills harmful bacteria that might be in the food.
What are reactants and products in a chemical reaction?
Reactants are the starting substances in a chemical reaction, which undergo change.
Products are the new substances formed as a result of the reaction.
What are some common unhealthy lifestyle choices?
Poor diet: Eating too much junk food, processed food, or sugary drinks.
Lack of exercise: Not engaging in enough physical activity.
Smoking: Inhaling tobacco, which can damage the lungs and increase the risk of diseases like cancer.
Excessive alcohol consumption: Drinking too much alcohol can harm the liver and increase the risk of accidents.
Poor sleep habits: Not getting enough rest, which affects mental and physical health.