Substances in Common Use — Maharashtra (SSC) Class 9 Science Solutions (Free)
Free step-by-step Maharashtra (SSC) Class 9 Science solutions for "Substances in Common Use" — important questions with detailed answers, download PDF for board exam preparation.
TL;DR: Free step-by-step Maharashtra (SSC) Class 9 Science solutions for "Substances in Common Use" — important questions with detailed answers, download PDF…
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Q1: What is a soap? How is soap prepared?
Soap is a salt of a higher fatty acid, used for cleaning. Preparation: When an ester (fat or oil) reacts with sodium hydroxide solution, it undergoes saponification, producing glycerol and soap. This reaction is called ester hydrolysis or saponification reaction.
Q2: How does soap cleanse dirt and oil?
Soap has two ends: hydrophobic tail (water-repelling) attaches to oil/dirt, and hydrophilic head (water-attracting) dissolves in water. This forms micelles where oil is trapped inside, allowing dirt to mix with water and be washed away during rinsing.
Q3: What is the composition and uses of glass?
Glass is made from silica sand (SiO2), soda ash (Na2CO3), and limestone (CaCO3) heated to high temperature. Uses: window panes for buildings, bottles for storage, laboratory apparatus, optical lenses, and decorative items.
Q4: Explain the manufacturing of cement and its uses.
Cement is made by heating limestone and clay at very high temperatures in a kiln, then grinding with gypsum. Uses: Concrete and mortar for construction, binding material in buildings, roads, bridges, and dams. It hardens when mixed with water.
Q5: What are fertilisers? Name two types and their functions.
Fertilisers are substances added to soil to increase plant growth and crop yield. Types: Nitrogenous fertilisers (urea, ammonium nitrate) provide nitrogen for leaf growth. Phosphatic fertilisers (superphosphate) promote root development and flowering.
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