• Salts & pH: Strong acid + strong base → neutral salt (pH 7); strong acid + weak base → acidic salt (pH < 7); weak acid + strong base → basic salt (pH > 7).
• Common salt (NaCl): neutral, crystalline; made by neutralization or obtained from sea/rock salt. Electrolysis of brine: \( \mathrm{2NaCl+2H_2O \rightarrow 2NaOH+Cl_2+H_2} \).
• Baking soda (NaHCO₃): mild basic; uses—baking (CO₂ release), antacid, in some fire extinguishers (gives CO₂).
• Bleaching powder (CaOCl₂): releases \( \mathrm{Cl_2} \) slowly; prepared by \( \mathrm{Ca(OH)_2 + Cl_2 \rightarrow CaOCl_2 + H_2O} \); disinfectant & bleaching agent.
• Washing soda (Na₂CO₃·10H₂O): softens hard water by precipitating Ca/Mg carbonates; effloresces to monohydrate/anhydrous (soda ash).
• Crystalline salts with water of crystallization: Alum, Borax, Epsom salt, Barium chloride, Glauber’s salt—specific uses in water treatment, labs, etc.
• Radioactivity: Spontaneous emission (α, β, γ); applications in industry (radiography, thickness gauges), agriculture (food irradiation), medicine (diagnosis/therapy). Hazards demand shielding & safety.
• Food colours & dyes: Prefer natural colours; excessive artificial colours may cause health issues (e.g., ADHD risk, heavy metal exposure).
• Deodorants: May contain alcohol, parabens, aluminium salts; overuse can irritate skin; antiperspirants plug sweat pores.
• Teflon (PTFE): non-stick, chemically inert, high mp (~\(327^\circ\)C), poor conductor—uses: cookware, wiring, automotive coatings.
• Powder coating: Electrostatic spray + heat cure → tough, uniform, anti-corrosion finish.
• Anodizing (Al): Electrolytic thickening of \( \mathrm{Al_2O_3\cdot xH_2O} \) layer → corrosion resistant, can be coloured.
• Ceramics: Heat-resistant, brittle, electrical insulators; include porcelain, bone china, advanced ceramics (Al₂O₃, ZrO₂, SiC, B₄C) used in kilns, engines, electronics.

1) Formula of common salt?

NaCl (sodium chloride), neutral salt.

2) Chemical name of baking soda?

Sodium hydrogen carbonate (sodium bicarbonate), \( \mathrm{NaHCO_3} \).

3) Chemical name of washing soda?

Sodium carbonate decahydrate, \( \mathrm{Na_2CO_3\cdot 10H_2O} \).

4) Bleaching powder formula?

\( \mathrm{CaOCl_2} \) (calcium oxychloride).

5) pH of neutral salt solution (strong acid + strong base)?

7 (neutral).

6) Brine means?

Concentrated/saturated aqueous solution of NaCl.

7) Gas at anode during brine electrolysis?

Chlorine, \( \mathrm{Cl_2} \).

8) Main component released from baking powder in cake?

Carbon dioxide gas, \( \mathrm{CO_2} \).

9) Hardness causing ions?

Ca²⁺ and Mg²⁺ (as chlorides/sulphates).

10) One use of alum in water works?

Coagulation—settles suspended impurities.

11) Nature of α rays?

He²⁺ nuclei; heavy, low penetration, high ionization.

12) Nature of β rays?

Electrons; moderate penetration; deflect towards + plate.

13) Nature of γ rays?

EM radiation; very high penetration; no charge.

14) Full form of PTFE?

Polytetrafluoroethene (Teflon).

15) One key property of Teflon for cookware?

Non-stick (oil/water don’t adhere) and chemically inert.

16) What is powder coating?

Electrostatic deposition of polymer powder followed by heat curing.

17) Anodizing improves what?

Corrosion resistance and appearance of aluminium.

18) Porcelain main clay?

Kaolin (china clay).

19) One hazard of excessive artificial food colours?

Potential behaviour/attention issues; heavy metal exposure.

20) Why deodorants may irritate skin?

Alcohol/parabens/aluminium salts can cause irritation or pore blockage.

1) Write the brine electrolysis overall reaction.

\( \mathrm{2NaCl + 2H_2O \rightarrow 2NaOH + Cl_2 + H_2} \).

2) What happens when CaOCl₂ is exposed to air CO₂?

Releases \( \mathrm{Cl_2} \) and forms \( \mathrm{CaCO_3} \): \( \mathrm{CaOCl_2 + CO_2 \rightarrow CaCO_3 + Cl_2} \).

3) Why does washing soda soften hard water?

Precipitates Ca²⁺/Mg²⁺ as insoluble carbonates.

4) Reaction for MgCl₂ (aq) with Na₂CO₃ (aq).

\( \mathrm{MgCl_2 + Na_2CO_3 \rightarrow MgCO_3\downarrow + 2NaCl} \).

5) What is water of crystallization?

Fixed number of water molecules integrated in a crystal lattice.

6) Example of a salt with 10 waters of crystallization.

Glauber’s salt \( \mathrm{Na_2SO_4\cdot 10H_2O} \) or washing soda \( \mathrm{Na_2CO_3\cdot 10H_2O} \).

7) Define radioactivity.

Spontaneous emission of radiation from unstable nuclei.

8) Which radiation is most penetrating?

Gamma (γ) rays.

9) One medical use of radioactive isotopes.

Cancer diagnosis/therapy (e.g., Co-60, I-131).

10) One agricultural use of radiation.

Food preservation/anti-sprouting (Co-60 γ-irradiation).

11) Why prefer natural food colours?

Safer; fewer toxic additives/heavy metals.

12) What is a dye?

Colouring substance that imparts colour to materials (often water-soluble).

13) Why does antiperspirant deo reduce sweat?

Aluminium salts plug sweat pores temporarily.

14) PTFE melting point (approx.)?

\( \approx 327^\circ \mathrm{C} \).

15) Core idea of powder coating adhesion.

Electrostatic charge causes powder to stick uniformly to metal.

16) Gas at cathode during anodizing cell?

Hydrogen (H₂).

17) Porcelain main traits.

Hard, white, translucent ceramic made with kaolin.

18) One property of advanced ceramics.

High-temperature strength; wear/heat resistance.

19) One hazard of radioactive fallout in oceans.

Bioaccumulation in fish → human exposure.

20) Why soap lathers poorly in hard water?

Forms insoluble Ca/Mg soaps (precipitate), reducing lather.

1) Classify salts by pH with an example each.

Neutral (NaCl), Acidic (NH₄Cl from strong acid + weak base), Basic (CH₃COONa from weak acid + strong base).

2) Explain the porous nature of cakes with baking soda.

Thermal/acidic decomposition of \( \mathrm{NaHCO_3} \) releases \( \mathrm{CO_2} \) which makes bubbles → porous, fluffy texture.

3) Write preparation and one use of bleaching powder.

Prep: \( \mathrm{Ca(OH)_2 + Cl_2 \rightarrow CaOCl_2 + H_2O} \). Use: Disinfection of drinking/swimming pool water.

4) How does washing soda treat hard water?

Carbonate ions precipitate Ca²⁺/Mg²⁺ as carbonates; water becomes soft and forms lather with soap.

5) State two salts with water of crystallization and uses.

Alum (water purification); Epsom salt (in baths/medicine as directed).

6) Differentiate α, β, γ based on charge & deflection.

α: +2, deflect to − plate (slight); β: −1, deflect to + plate (more); γ: 0, no deflection.

7) One industrial and one medical use of radioisotopes.

Industrial radiography (Co-60); thyroid diagnosis/therapy (I-131/I-123 as per context).

8) Mention two hazards of radiation.

DNA damage (hereditary defects), cancers (leukaemia/skin).

9) Suggest safer alternatives to artificial food colours for festivals.

Use beetroot, turmeric, spinach, marigold, palash (flame-of-forest) extracts.

10) Why can deodorants be problematic for adolescents?

Excess alcohol/aluminium salts may irritate skin, clog pores; fragrance allergens possible.

11) What makes Teflon suitable for non-stick cookware?

Low surface energy (nothing sticks), chemical inertness, thermal stability.

12) Outline powder coating steps briefly.

Clean & prep → electrostatic spray powder → heat cure → cross-linked tough film.

13) Explain anodizing principle on aluminium.

Al acts as anode in electrolyte; oxygen at anode forms thicker hydrated alumina layer → protective & dyeable.

14) What is ceramic glaze and why applied?

Finely ground glass slurry; on firing seals pores, gives shiny, non-porous surface.

15) Distinguish porcelain and bone china.

Both from kaolin; bone china includes bone ash → lighter yet strong, more translucent.

16) Write a balanced reaction showing Na₂CO₃ with H₂SO₄.

\( \mathrm{Na_2CO_3 + H_2SO_4 \rightarrow Na_2SO_4 + H_2O + CO_2} \).

17) Explain “efflorescence” of washing soda.

\( \mathrm{Na_2CO_3\cdot 10H_2O} \) loses water to air → monohydrate/anhydrous form (powdery “soda ash”).

18) State two reasons to avoid heavy-metal-laden colours.

Toxicity (mercury/lead), long-term neurological/organ damage.

19) Give one reason α rays have high ionization but low penetration.

Large mass/charge → strong interaction with matter (ionize quickly) and lose energy rapidly.

20) Why do soaps form scum in hard water?

Insoluble calcium/magnesium soaps precipitate as scum, wasting soap.

1) Fill in the blanks.

a) Washing soda has 10 molecules of water of crystallization (Na₂CO₃·10H₂O).
b) Baking soda’s chemical name is sodium hydrogen carbonate (sodium bicarbonate).
c) Iodine-123 (diagnosis) / Iodine-131 (therapy) is used in the context of the thyroid; for hyperthyroidism treatment generally I-131 is used.
d) The chemical name of Teflon is polytetrafluoroethene (PTFE).

2) Match the pairs.

1) Saturated brine → c. crystallization of salt (source/medium for NaCl and electrolysis).
2) Fused salt → a. sodium metal freed (molten NaCl electrolysis: Na(l) at cathode).
3) CaOCl₂ → d. oxidation of colour (bleaching/disinfection via chlorine release).
4) NaHCO₃ → b. basic salt (mildly basic; used in baking/antacid).
(Extra stems in text align: e) anodizing anode is aluminium; f) three marks on plate show α, β, γ; g) ceramic tiles on space shuttle.)

3) Write answers to the following.

a) Radioactivity: Spontaneous emission of α, β, γ from unstable nuclei.
b) Unstable nucleus: Excess energy/neutron-proton imbalance → tends to attain stability by emitting radiation/particles.
c) Diseases by artificial food colours: Potential hyperactivity/attention issues in children, allergies; heavy-metal contamination may harm organs.
d) Industrial uses: Radiography (Co-60), thickness/level gauges, radioluminescent paints, HID lamps (Kr-85), portable β sources (Pm-147).
e) Teflon properties: Chemically inert, non-stick (low surface energy), poor electrical conductor, high melting point (~\(327^\circ\)C), easy to clean.
f) Eco-friendly Rang Panchami colours: Use natural colours (beetroot, turmeric, palash, spinach) to avoid toxic effects of synthetic dyes.
g) Why Teflon coating common? Enhances durability, heat/chemical resistance, non-stick surface—useful for cookware, auto and electronics.

4) Give scientific explanation.

a) Bleaching powder smells of chlorine as it liberates \( \mathrm{Cl_2} \) slowly in moist air/CO₂.
b) Hard well water softens with washing soda as \( \mathrm{CO_3^{2-}} \) precipitates Ca²⁺/Mg²⁺ as carbonates.
c) Soap forms precipitate in hard water due to insoluble Ca/Mg soaps.
d) Powder coating uses charged particles so that electrostatic attraction ensures uniform adhesion before curing.

5) Write answers.

a) Artificial food colours & harms: Synthetic dyes (e.g., sunset yellow, tartrazine) may contain contaminants; overuse linked to behavioural issues/allergies—prefer regulated, minimal use or natural colours.

b) Water of crystallization: Water molecules bound in crystal lattice—e.g., \( \mathrm{Na_2SO_4\cdot 10H_2O} \) (Glauber’s salt), \( \mathrm{CuSO_4\cdot 5H_2O} \) (blue vitriol), \( \mathrm{Na_2CO_3\cdot 10H_2O} \) (washing soda). Uses: lab reagents, water treatment, industry.

c) Three sodium chloride processes: (i) Crystallization from saturated brine; (ii) Electrolysis of brine to obtain \( \mathrm{Cl_2} \), \( \mathrm{H_2} \), \( \mathrm{NaOH} \); (iii) Electrolysis of fused (molten) NaCl to obtain sodium metal and \( \mathrm{Cl_2} \).

6) Write the uses.

a) Anodizing: Improves corrosion resistance/appearance of Al utensils, frames, electronics.
b) Powder coating: Durable anti-corrosion finish on appliances, furniture, auto parts, even MDF/plastic.
c) Radioactive substances: Medical imaging/therapy, industrial radiography, gauges, agriculture/food irradiation.
d) Ceramic: Electrical insulators, kiln linings, tiles, engine parts, shuttle heat-shields, superconductors (some types).

7) Write the harmful effects.

a) Artificial dyes: Skin/eye irritation, possible toxic impurities; environmental impact if plant sources over-harvested.
b) Artificial food colours: Possible behavioural effects in kids, allergies; heavy-metal contamination risks.
c) Radioactive substances: CNS effects, cancers, genetic damage; bioaccumulation via food chains.
d) Deodorants: Skin irritation/allergy; aluminium salts may block pores; overuse of aerosols affects air quality.

8) Write the chemical formula.

Bleaching powder: \( \mathrm{CaOCl_2} \); Common salt: \( \mathrm{NaCl} \); Baking soda: \( \mathrm{NaHCO_3} \); Washing soda: \( \mathrm{Na_2CO_3\cdot 10H_2O} \).

9) Explain what you see in the following picture (α, β, γ separation setup).

A radioactive source emits mixed radiation through a slit; in an electric field, α (positive) bends slightly towards the negative plate, β (negative) bends strongly towards the positive plate, and γ (neutral EM wave) goes straight—recorded as three distinct traces on a ZnS-coated photographic plate.

• Brine electrolysis: \( \displaystyle \mathrm{2NaCl+2H_2O \rightarrow 2NaOH+Cl_2+H_2} \)
• Molten NaCl electrolysis (overall): \( \displaystyle \mathrm{2NaCl \rightarrow 2Na + Cl_2} \)
• Bleaching powder prep: \( \displaystyle \mathrm{Ca(OH)_2 + Cl_2 \rightarrow CaOCl_2 + H_2O} \)
• CO₂ release from CaOCl₂ in air: \( \displaystyle \mathrm{CaOCl_2 + CO_2 \rightarrow CaCO_3 + Cl_2} \)
• Softening: \( \displaystyle \mathrm{MgCl_2 + Na_2CO_3 \rightarrow MgCO_3\downarrow + 2NaCl} \)
• Acid + carbonate: \( \displaystyle \mathrm{Na_2CO_3 + H_2SO_4 \rightarrow Na_2SO_4 + H_2O + CO_2} \)