CG Board Class 9 Science Chapter 2 Solutions: Matter: Nature and Behaviour (पदार्थ: प्रकृति एवं व्यवहार) – 2026-27

Identify matter from among the following: water, air, chair, stone, scent of a flower, iron, thoughts.

Anything that occupies space and has mass is called matter.

• Matter: Water, air, chair, stone, scent of a flower (due to volatile substance particles present in air), iron.
• Not Matter: Thoughts (neither occupies space nor has mass).

20 g ‘A’ and 40 g ‘B’ give 25 g ‘C’, 15 g ‘D’ and 20 g ‘E’ in a reaction. Use these observations to explain the law of conservation of mass.

• Total mass of reactants = Mass of A + Mass of B = 20 g + 40 g = 60 g.
• Total mass of products = Mass of C + Mass of D + Mass of E = 25 g + 15 g + 20 g = 60 g.
• Since the total mass of reactants equals the total mass of products (60 g = 60 g), this demonstrates the Law of Conservation of Mass formulated by Lavoisier, which states that mass can neither be created nor destroyed during a chemical reaction.

Identify solutions, suspensions and colloids from among the given mixtures: salt dissolved in water, mud in water, milk in water.

Which amongst the following mixtures will show Tyndall effect: sugar in water, ink in water, starch हल, salt हल.

Ink in water and Starch हल will show the Tyndall effect because they are colloidal solutions containing particles large enough to scatter a beam of light.

250 g of washing soda was dissolved in 1 kg of water. Find the concentration of the हल in terms of mass percentage.

• Mass of solute (washing soda) = 250 g
• Mass of solvent (water) = 1 kg = 1000 g
• Mass of हल = Mass of solute + Mass of solvent = 250 g + 1000 g = 1250 g
• Mass percentage = (Mass of solute / Mass of हल) * 100
• Mass percentage = (250 / 1250) 100 = (1 / 5) 100 = 20%.

When we add 1-2 drops of rice water (pasiya) in 100 mL water, what do we get: a colloid or a suspension? Explain with reasons.

• We get a colloid.
• Reason: Rice water contains starch particles dispersed in water. The particle size is intermediate (between a true हल and a suspension). The particles do not settle down under gravity, cannot be filtered out by filter paper, and scatter light to exhibit the Tyndall effect.

Group the following substances into elements or compounds: potassium, lime water, sulphur, washing soda, carbon, lead, vinegar.

We get a white powder when we burn magnesium ribbon in air. Is this powder an element or a compound? Give reasons for your answer.

• The white powder is a compound (Magnesium Oxide – MgO).
• Reason: Magnesium reacts chemically with oxygen present in the air in a fixed mass ratio to form a new substance whose chemical properties are completely different from both magnesium metal and oxygen gas.

What is common salt: element, compound or mixture? Explain.

• Common salt is a compound (Sodium Chloride – NaCl).
• Reason: It is formed by the chemical combination of two elements, sodium (Na) and chlorine (Cl), in a fixed ratio by mass. Its constituent elements cannot be separated by physical separation methods.

(i) Homogeneous mixture is / समांगी मिश्रण है:**

(ii) Heterogeneous mixture is / विषमांगी मिश्रण है:

(iii) Oxygen is / ऑक्सीजन है:

(iv) Sugar is / शक्कर है:

(v) Which of the following will show Tyndall effect / निम्नलिखित में से कौन टिंडल प्रभाव दर्शाएगा:

(vi) Which of the following is not a pure substance / निम्नलिखित में से कौन शुद्ध पदार्थ नहीं है:

• Solutions / विलयन:

1. Sea water / समुद्री जल: Homogeneous liquid हल of salts dissolved in water.
2. Air / वायु: Homogeneous gaseous हल of nitrogen, oxygen, and trace gases.
3. Soda water / सोडा वाटर: Homogeneous हल of carbon dioxide gas dissolved in water.

• (Note: Soil is a heterogeneous mixture, whereas glue in water and milk in water are colloids).

• Elements / तत्व: तांबा, हीरा, नियॉन गैस, एल्युमिनियम, चांदी, सोडियम.
• Compounds / यौगिक: नमक, शुद्ध जल, साबुन, कार्बन डाइऑक्साइड.
• Mixtures / मिश्रण: शिकंजी, चट्टानें, सलाद, रक्त.

(i) An element has ………………………… type of particles (same/different).**

(ii) The scattering of light by colloid particles is called …………………………….. (Tyndall effect/ Brownian motion).

(iii) In tincture iodine solution, iodine is the ………………………….. (solvent/ solute).

(iv) The particles in a ………………………… can be separated by filtration using filter paper (suspension/ colloid).

(v) Particles in a ……………………………………. cannot be seen with the naked eye (solution/ suspension).

Substances made up of only one type of particles (atoms or molecules) with a definite chemical composition and uniform properties. They cannot be separated into simpler constituents by physical methods. Examples: Iron, Pure Water, Sodium Chloride.

A हल in which no more solute can be dissolved at a given temperature. Example: Adding table salt to water at room temperature until added salt stops dissolving and remains at the bottom.

A heterogeneous mixture where solute particle sizes are intermediate (between solutions and suspensions). Particles do not settle down under gravity, pass through filter paper, but scatter light beams showing the Tyndall effect. Examples: Milk, Ink in water, Fog.

A heterogeneous mixture in which solute particles do not dissolve, remain suspended in the medium, are visible to the naked eye, and settle down if left undisturbed. Examples: Muddy water, Chalk powder in water.

• English Activity:

1. Take 100 mL of clean water in a glass beaker and add one spoonful of sugar.
2. Stir vigorously with a glass rod until the sugar disappears completely.
3. Observations:

• The mixture appears uniform throughout (homogeneous).
• Sugar particles are invisible even under a microscope.
• Direct a laser beam through the beaker: the path of light is invisible inside the liquid.
• Taste samples from the top, middle, and bottom: it tastes uniformly sweet throughout.
• Pass the liquid through filter paper: no sugar residue remains on the filter paper.

1. Conclusion: Because the constituent particles are uniformly distributed, do not settle down, do not scatter light, and pass through filter paper, sugar dissolved in water is a true हल.

• Hindi Activity / हिंदी गतिविधि:

1. एक कांच के बीकर में 100 mL स्वच्छ जल लें और उसमें एक चम्मच शक्कर मिलाएं।
2. कांच की छड़ से तब तक हिलाएं जब तक कि शक्कर पूरी तरह गायब न हो जाए।
3. प्रेक्षण:

• संपूर्ण मिश्रण एकसमान दिखाई देता है (समांगी)।
• शक्कर के कण सूक्ष्मदर्शी से भी दिखाई नहीं देते।
• लेजर टॉर्च से प्रकाश की किरण गुजारें: बीकर के द्रव में प्रकाश का मार्ग दिखाई नहीं देता।
• विलयन को ऊपर, मध्य और नीचे से चखें: इसका स्वाद हर जगह एकसमान मीठा होता है।
• इसे फ़िल्टर पेपर से छानें: फ़िल्टर पेपर पर कोई अवशेष नहीं बचता।

1. निष्कर्ष: चूंकि अवयवी कण समान रूप से वितरित हैं, नीचे नहीं बैठते, प्रकाश का प्रकीर्णन नहीं करते तथा फ़िल्टर पेपर से छन जाते हैं, इसलिए जल में घुली शक्कर एक वास्तविक विलयन है।

The solubility of most solids in liquids increases with an increase in temperature.

• English Question: Seema took three solids A, B and C and made their saturated solutions in 100 g water at different temperatures. The amounts of A, B and C used to form saturated solutions are shown in the table:

Table / तालिका:

• Solute A: 293 K = 35 g | 313 K = 36 g | 333 K = 37 g | 353 K = 38 g
• Solute B: 293 K = 32 g | 313 K = 62 g | 333 K = 106 g | 353 K = 167 g
• Solute C: 293 K = 34 g | 313 K = 40 g | 333 K = 46 g | 353 K = 54 g