Ans: The formula of carbon dioxide gas that we exhale is (CO2)
(ii) Define the element, compound and mixture.Element: A pure thing made of one kind of atom. It can't break into simpler parts. (Example: Oxygen, O)
Compound: A mix of two or more different elements that join in fixed amounts. (Example: Water, H₂O)
Mixture: Two or more things put together but not joined chemically. You can separate them. (Example: Saltwater)
Compound: A substance made when different elements bond chemically in fixed ratios.
Mixture: A combination of substances mixed physically, not chemically bonded.
Compound: Formed through chemical reactions with bonds like ionic, covalent, or metallic.
Mixture: Formed by simply mixing substances without chemical changes.
Compound: Has fixed, definite proportions.
Mixture: Can have any proportion of components.
Compound: Has new physical and chemical properties.
Mixture: Retains the properties of its components.
Compound: Separated only by chemical reactions.
Mixture: Separated by physical methods like filtration or distillation.
Compound: Water (H₂O) - Fixed ratio of hydrogen and oxygen.
Mixture: Air - A mix of gases like nitrogen, oxygen, and CO₂.
Compound: Always the same throughout (homogeneous).
Mixture: Can be uniform (homogeneous) or non-uniform (heterogeneous).
Compound: Formation involves energy changes.
Mixture: Mixing usually does not require much energy.
| Aspect | Concentrated Solution | Dilute Solution |
|---|---|---|
| Definition | A solution with a high amount of solute relative to solvent. | A solution with a low amount of solute relative to solvent. |
| Solute Amount | High solute content. | Low solute content. |
| Solvent Amount | Less solvent. | More solvent. |
| Concentration | High solute concentration. | Low solute concentration. |
| Example | Strong saltwater solution. | Weak saltwater solution. |
| Taste | Stronger taste (e.g., concentrated lemon juice is very sour). | Milder taste (e.g., diluted lemon juice is less sour). |
| Viscosity | Can be thicker (e.g., syrup). | Closer to water’s viscosity. |
| Boiling Point | Higher than pure solvent. | Lower, closer to pure solvent. |
| Freezing Point | Lower than pure solvent. | Higher, closer to pure solvent. |
| Uses | Used in industrial processes. | Used in cooking and drinking. |
Ans: See Question 5 in theory
4. What is the difference between Homogeneous and Heterogeneous solutions?Here’s a simple way to understand the difference between homogeneous and heterogeneous mixtures.
| No. | Solution | Colloids | Suspension |
|---|---|---|---|
| 1 | A homogeneous mixture of two or more components. | A heterogeneous mixture of two or more components. | A heterogeneous mixture of two or more components. |
| 2 | Particle size < 1 nm. Not visible to the naked eye. | Particle size between 1-10 nm. Visible under certain conditions. | Particle size > 10 nm. Visible to the naked eye. |
| 3 | Particles pass through normal and ultra-filter paper. | Particles pass through normal filter paper but not ultra-filter paper. | Particles do not pass through normal filter paper. |
| 4 | Does not scatter light. | Scatters light (Tyndall effect). | Scatters light (Tyndall effect). |
| 5 | Does not separate over time. | Does not separate over time. | Separates or settles when left undisturbed. |
| 6 | Example: Sea water. | Example: Milk. | Example: Muddy water. |
An element's atomic number is the count of protons in its nucleus. Since Argon has 18 protons, its atomic number is 18.
Ans: See Question 2 in theory
8. Differentiate between the followingAns: See theory Question No.
10. Why is a solution considered mixture?A solution is a mixture because it combines two or more substances (solute and solvent) without any chemical change. The solute spreads out evenly in the solvent at a tiny level, but both keep their original properties. No new substance forms.
You can separate a solution into its parts using simple methods like evaporation or distillation. This is a key trait of mixtures.
To check if a solution is a colloid or a true solution, we use the Tyndall Effect.
Liquids move easily because they have low thickness and no set shape. Solids, on the other hand, keep their shape and resist movement more.
Pouring juice is simple since it flows smoothly when you tilt the container. But sliding a block of cheese on a table takes more effort because it is solid and does not flow.
Different liquids flow at different speeds because of their thickness, called viscosity. Viscosity depends on how the liquid’s molecules move and how hot the liquid is.
For example, juice flows easily because its molecules move past each other easily. Honey, however, flows slowly because its molecules are thicker and stick together more. The way molecules move and stick together determines how fast a liquid can flow.
Exotic states of matter are different from basic states. These states have special properties and need extreme conditions to exist. Basic states include solids, liquids, gases, and plasmas. These are common and behave in familiar ways. Exotic states, like Bose-Einstein condensates and fermionic condensates, happen under very cold or very high pressure. These states can show strange behaviors like superfluidity and superconductivity. They help scientists discover new physics that goes beyond what we know about regular matter.
Liquid crystals are different from regular liquids because their molecules are partly ordered. This allows them to align in certain directions, while still being able to flow. Regular liquids have molecules that are randomly arranged. Liquid crystals can change their optical properties when exposed to electric fields or temperature changes. This makes them very important in LCD screens, where they help control light to form images and text. Their unique phases and properties allow precise control of light, setting them apart from regular liquids.
Plasma can be found in nature, like in lightning or the Northern Lights. You can also see it in things like neon signs and plasma TVs. Plasma is different from solids, liquids, and gases. It is made of gas that has been charged, with free electrons and ions. This makes plasma able to carry electricity and react to magnetic fields. Plasma can also shine and create electromagnetic fields. Its high energy makes it very special compared to other types of matter.
A mixture of sulfur and iron powders contains two substances that are simply mixed together. They do not change chemically. Each substance keeps its own properties. You can easily separate them using methods like a magnet.
But iron sulfide is different. It forms when iron and sulfur are heated together. This causes a chemical reaction. A new substance is made, and its properties are different. The iron and sulfur bond together in a fixed way.
Iron sulfide cannot be separated easily like a mixture. Its physical and chemical properties are not the same as those of iron and sulfur.
Sugar dissolves in water because its tiny molecules mix completely with the liquid. This creates a clear and even solution.
Orange juice, however, contains pulp, fibers, and oils. These do not dissolve fully, making the liquid cloudy. This type of mixture is called heterogeneous.
In orange juice, tiny solid pieces spread throughout the liquid and scatter light. That’s why it looks cloudy. In contrast, sugar water stays clear because no solid particles are left floating around.
In short, sugar water is a smooth solution, while orange juice is a mix of solid pieces in liquid.
Sugar in Water: Sugar dissolves completely, creating a clear liquid. This is called a solution.
Orange Juice: It contains tiny pulp particles that stay mixed and do not settle. This is a colloid.
Fog and smoke are both examples of colloids, specifically aerosols. In these mixtures, tiny liquid (fog) or solid (smoke) particles spread through the air. They make the air look hazy because they scatter light.
Fog forms when small water droplets mix with air, while smoke contains solid or liquid particles in the air. These particles are larger than those in solutions but smaller than those in suspensions. This is why fog and smoke do not mix completely like air but do not settle like heavier particles.
Clean air, on the other hand, is a smooth mixture of gases without visible particles. Because it has no scattered light, it looks clear.
Sand in water is a suspension. You can see the sand particles, and they slowly settle at the bottom due to gravity.
Milk is an emulsion, a special kind of mixture. Tiny fat droplets spread throughout the liquid, and they do not settle. This happens because of their small size and how they mix with other parts of the milk.
When the temperature rises, molecules move faster. This extra movement helps break cocoa powder apart and spread it into the milk. That’s why hot milk dissolves more cocoa than cold milk.
Diamond has carbon atoms arranged in a strong 3D tetrahedral structure. Graphite has carbon atoms in flat hexagonal layers that slide over each other. Fullerenes, like buckminsterfullerene (C60), have carbon atoms forming a spherical shape.
Yes! Allotropy happens in many elements, not just carbon. For example:
These forms have different properties but are still the same element!
Metallic Elements: Calcium, Iron, Copper.
Non-Metallic Elements: Silicon, Argon, Sulfur, Nitrogen, Diamond.
Compounds: Water, Carbon Monoxide, Sodium Chloride, Sulfuric Acid, Ammonia.
Mixtures: Sea Water, Air, Brass, Oil.
Definition: Elements are pure substances that cannot be broken down into simpler ones using chemical methods.
Composition: Made of only one type of atom.
Example: Iron (Fe)
Properties: Defined by the number of protons in its nucleus.
Definition: A compound is a substance made of two or more different elements that are chemically bonded in a fixed ratio.
Composition: Contains atoms of different elements joined together.
Example: Water (H₂O)
Properties: Compounds have unique properties different from their elements.
Separation: Can only be broken down by chemical reactions.
Definition: A mixture consists of two or more substances (elements or compounds) that are physically combined, not chemically.
Separation: Mixtures can be separated using physical methods.
Ans: See theory Question No.
In a mixture, each substance keeps its own chemical properties. You can usually separate the components using physical methods.
You can often separate mixtures using physical methods like filtration, evaporation, or distillation.
Mixtures have two or more substances that are physically combined but not chemically bonded.
Air is a mixture.
Temperature has a big effect on how well a solid can dissolve in a liquid. Solubility is the amount of solute that can dissolve in a solvent at a certain temperature and pressure. Here's how temperature affects this:
Solubility is like a balance between the solute dissolving and the solute coming back out of the solution. At higher temperatures, the balance shifts to more dissolving because:
In short, temperature plays a big role in how much solid can dissolve in a liquid. As the temperature rises, more solute typically dissolves. This is important in chemistry and many other areas.
Ans: To separate a mixture of sand, salt, and oil, we use the physical properties of each part. Here’s how it’s done:
Method: Decantation
Process: Oil floats on top of water because it is lighter. Gently tilt the container to pour the oil into a new one. The sand and salt stay behind.
Why it works: Oil is less dense than water and does not mix with it. This makes it easy to separate.
Method: Filtration
Process: Add water to the sand and salt mixture. Stir to dissolve the salt. Use a funnel with filter paper to strain it. The sand stays on the paper, and the saltwater goes through.
Why it works: Sand doesn’t dissolve in water, but salt does. This difference makes filtration useful.
Method: Evaporation
Process: Heat the saltwater solution. The water will evaporate, leaving salt crystals behind.
Why it works: Salt has a higher boiling point than water. By heating the water, it evaporates first, leaving the salt behind.
These steps use differences in density, solubility, and boiling points to separate the mixture.