Important Salts — Set 1
Chemistry · महत्वपूर्ण लवण · Questions 1–10 of 40
Which salt is commonly used in the purification of drinking water to remove suspended impurities?
Correct Answer: C. Potash Alum
• **Potash Alum** = acts as a coagulant that causes suspended particles to settle. • **Coagulation process** — removes fine impurities, turbidity, and colloidal matter from water. • 💡 Wrong-option analysis: Baking Soda: leavening agent, not a coagulant; Washing Soda: softens water but doesn't clarify it; Common Salt: increases salinity, used in industrial processes.
What is the chemical name of the salt used to make bread and cakes soft and spongy?
Correct Answer: A. Sodium Hydrogen Carbonate
• **Sodium Hydrogen Carbonate** = releases carbon dioxide gas when heated, creating bubbles. • **CO₂ production** — makes baked goods light, fluffy, and spongy through gas expansion. • 💡 Wrong-option analysis: Calcium Sulfate: used in plaster, not leavening; Calcium Oxychloride: a bleaching agent; Sodium Carbonate: leaves bitter taste, unsuitable for baking.
Which of the following salts is used as a dehydrating agent in the preservation of meat and fish?
Correct Answer: D. Sodium Chloride
• **Sodium Chloride** = draws out moisture from food via osmosis, preventing microbial growth. • **Dehydration mechanism** — creates hypertonic environment that inhibits bacteria and extends shelf life. • 💡 Wrong-option analysis: Sodium Sulfate: industrial use only, not food-safe; Sodium Acetate: a weak preservative, limited effectiveness; Sodium Nitrate: used differently in curing processes.
The salt used by doctors to set fractured bones and in making decorative statues is?
Correct Answer: C. Plaster of Paris
• **Plaster of Paris** = calcium sulfate hemihydrate that hardens rapidly when mixed with water. • **Quick-setting property** — hydrates to form calcium sulfate dihydrate, creating rigid casts for medical immobilization. • 💡 Wrong-option analysis: Bleaching Powder: disinfectant, not a binder; Epsom Salt: used for muscle relaxation, not structural support; Gypsum: the parent mineral, less processed than Plaster of Paris.
Which salt is an essential ingredient in the manufacture of glass, soap, and paper?
Correct Answer: A. Sodium Carbonate
• **Sodium Carbonate** = lowers the melting point of silica in glass production, acts as a flux. • **Multi-industry use** — essential in soap saponification, paper pulp processing, and textile production. • 💡 Wrong-option analysis: Sodium Chloride: electrolyzed to produce these chemicals, not a direct ingredient; Sodium Bicarbonate: decomposes at manufacturing temperatures; Sodium Hydroxide: produced from sodium carbonate, not as widely applicable.
What type of salt is formed when a strong acid reacts with a weak base?
Correct Answer: A. Acidic Salt
• **Acidic Salt** = forms because the strong acid's hydrogen ions remain un-neutralized by the weak base. • **pH < 7** — aqueous solution is acidic due to hydrolysis of the salt, releasing additional H+ ions. • 💡 Wrong-option analysis: Neutral Salt: requires equal strength acid and base; Double Salt: contains two different cations in a single crystal; Basic Salt: forms from weak acid and strong base.
Which salt is used in black and white photography due to its light-sensitive nature?
Correct Answer: D. Silver Bromide
• **Silver Bromide** = undergoes photolysis when exposed to light, depositing metallic silver on film emulsion. • **Image formation** — develops latent image through chemical reduction of AgBr crystals after light exposure. • 💡 Wrong-option analysis: Sodium Bromide: salt of alkali metal, not light-sensitive; Calcium Bromide: lacks photographic properties; Potassium Bromide: used in spectroscopy, not photography.
Which of the following salts is known as 'Blue Vitriol'?
Correct Answer: A. Copper Sulfate
• **Copper Sulfate** = pentahydrate form displays bright blue crystals due to hydrated Cu²+ ions. • **Historical naming** — 'vitriol' derives from old names for metal sulfates; blue color makes it unmistakable. • 💡 Wrong-option analysis: Magnesium Sulfate: white crystals (Epsom salt); Ferrous Sulfate: pale green color; Zinc Sulfate: colorless or white crystals.
Which salt is used as an antacid to neutralize excess acid in the stomach?
Correct Answer: B. Sodium Hydrogen Carbonate
• **Sodium Hydrogen Carbonate** = reacts with HCl in stomach, producing salt, water, and CO₂ gas. • **Gas relief mechanism** — CO₂ release causes belching that relieves gastric distension and bloating. • 💡 Wrong-option analysis: Sodium Carbonate: too alkaline, leaves unpleasant taste; Magnesium Hydroxide: thicker, chalky liquid antacid; Calcium Chloride: acidic, worsens acid reflux.
The salt present in the hard protective layer of human teeth and bones is?
Correct Answer: B. Calcium Phosphate
• **Calcium Phosphate** = primary mineral constituent of tooth enamel and bone matrix, providing hardness. • **Hydroxyapatite** — Ca₃(PO₄)₂ compound forms crystalline structure that gives skeletal rigidity and durability. • 💡 Wrong-option analysis: Sodium Phosphate: lacks mineralization properties, found mainly in blood; Calcium Carbonate: minor bone component, mostly in shells; Magnesium Carbonate: negligible role in skeletal structure.