Chemistry · Class 10 CBSE
A student compares diamond and graphite. Both are made only of carbon, yet diamond is extremely hard while graphite is soft and slippery. What is the best explanation?
A teacher demonstrates that cooking oil does not mix with water but forms tiny droplets when soap is added. Why does soap help remove oily stains?
Which carbon compound is most likely to be used as a fuel for cooking in homes because it burns with a clean flame?
A student adds a few drops of concentrated sulphuric acid to ethanol and heats the mixture carefully. Which product is formed?
A fruit juice is left uncovered for several days and develops a sour smell. Which compound is mainly responsible for this change?
A compound has the molecular formula C₂H₆. To which homologous series does it belong?
A student burns ethanol and notices a blue flame with very little smoke. Why is ethanol considered a good fuel?
A detergent is more effective than soap in hard water because:
Which statement correctly explains why carbon forms such a large number of compounds?
A student identifies an unknown liquid as ethanoic acid. Which observation would best support this conclusion?
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Why does carbon mainly form covalent bonds instead of ionic bonds?
2 marksExplain the cleaning action of soap using the concept of micelles.
2 marksDifferentiate between soap and detergent based on: - Behaviour in hard water - Environmental impact
2 marksWhy are homologous series useful for studying organic compounds?
2 marksState any two physical properties of covalent compounds and explain why they differ from ionic compounds.
2 marksExplain the unique properties of carbon that make it capable of forming millions of compounds. In your answer, include: - Tetravalency - Catenation - Covalent bonding - Examples of carbon compounds
5 marksDescribe the chemical properties of ethanol and ethanoic acid. Include: - Reaction of ethanol with sodium - Oxidation of ethanol - Reaction of ethanoic acid with sodium hydrogen carbonate - Esterification reaction with one use of esters
5 marksCase study: Rohan noticed that his mother used detergent to wash clothes when the household water supply was hard. She explained that soap was not very effective because it formed a white scum. During his science class, Rohan also learned that soaps contain molecules with a water-attracting end and an oil-attracting end. Answer the following questions: (a) Why does soap form scum in hard water?
1 markCase study: Rohan noticed that his mother used detergent to wash clothes when the household water supply was hard. She explained that soap was not very effective because it formed a white scum. During his science class, Rohan also learned that soaps contain molecules with a water-attracting end and an oil-attracting end. Answer the following questions: (b) Why do detergents clean clothes more effectively in hard water?
1 markCase study: Rohan noticed that his mother used detergent to wash clothes when the household water supply was hard. She explained that soap was not very effective because it formed a white scum. During his science class, Rohan also learned that soaps contain molecules with a water-attracting end and an oil-attracting end. Answer the following questions: (c) What are micelles, and how do they help remove oily dirt?
1 markCase study: Rohan noticed that his mother used detergent to wash clothes when the household water supply was hard. She explained that soap was not very effective because it formed a white scum. During his science class, Rohan also learned that soaps contain molecules with a water-attracting end and an oil-attracting end. Answer the following questions: (d) Mention one environmental concern associated with the excessive use of some synthetic detergents.
1 mark