Matter in Our Surroundings — Important Questions

Solid

Step 1: Let us recall the properties of each state of matter. Step 2: Solids have a fixed/definite shape and a definite volume. Their particles are tightly packed and held strongly together, so they resist changes in shape. Step 3: Liquids have a definite volume but NO definite shape — they take the shape of the container they are kept in. Step 4: Gases have neither a definite shape nor a definite volume — they fill up any container completely. Step 5: Therefore, only solids have both a definite shape AND a definite volume.

No definite shape but definite volume

Step 1: When you pour water from a glass into a bowl, the water takes the shape of the bowl. This means liquids do NOT have a definite shape. Step 2: However, if you measure 50 mL of water and pour it into different containers, it remains 50 mL. This means liquids DO have a definite volume. Step 3: So the correct description of a liquid is: no definite shape but definite volume. Step 4: Solids have both definite shape and volume. Gases have neither. This makes liquids unique — they can flow (they are fluids) but their volume stays fixed.

Solid

Step 1: The force of attraction between particles holds them together and determines how closely they are packed. Step 2: In solids, particles are very closely packed and the force of attraction between them is maximum. This is why solids are rigid and hard to compress. Step 3: In liquids, the force of attraction is intermediate — particles are close but can slide over each other. Step 4: In gases, the force of attraction is minimum — particles are far apart and move freely and randomly. Step 5: So the correct order of force of attraction is: Solid > Liquid > Gas.

0°C (273 K)

Step 1: The melting point is the minimum temperature at which a solid melts to become a liquid at atmospheric pressure. Step 2: For ice (solid water), this temperature is 0°C, which is equal to 273.15 K (approximately 273 K). Step 3: The boiling point of water is 100°C (373 K) — this is when water changes to steam, not when ice melts. Step 4: At exactly 0°C, ice starts melting. The temperature stays at 0°C until ALL the ice has melted — this is because the heat is used up as latent heat of fusion to break the bonds between particles. Step 5: So the melting point of ice = 0°C = 273 K.