Explain the formation of scum when hard water is treated with soap.
Explain the formation of scum when hard water is treated with soap.
Solution and Explanation
Soap does not work properly when the water is hard. A soap is a sodium or potassium salt of long chain fatty acids. Hard water contains salts of calcium and magnesium. When soap is added to hard water, calcium and magnesium ions present in water displace sodium or potassium ions from the soap molecules forming an insoluble substance called scum. A lot of soap is wasted in the process.
Top Questions on Chemical Properties Of Carbon Compounds
- Carbon compounds :
(i) are good conductors of electricity.
(ii) are bad conductors of electricity.
(iii) have strong forces of attraction between their molecules.
(iv) have weak forces of attraction between their molecules.
The correct statements are :- CBSE Class X - 2024
- Science
- Chemical Properties Of Carbon Compounds
- Consider the following statements about homologous series of carbon compounds:
(a) All succeeding members differ by –CH2 unit.
(b) Melting point and boiling point increases with increasing molecular mass.
(c) The difference in molecular masses between two successive members is 16 u.
(d) C2H2 and C3H4 are NOT the successive members of alkyne series.
The correct statements are –- CBSE Class X - 2024
- Science
- Chemical Properties Of Carbon Compounds
- (a) (i)Give reason why carbon can neither form C4+ cations nor C4− anions but form covalent compounds.
(ii) What is homologous series of carbon compound? Write the molecular formula of any two consecutive members of homologous series of aldehydes.
(iii) Draw the structure of the molecule of cyclohexane (C6H12).
OR
(b) (i) Name a commercially important carbon compound having functional group –OH and write its molecular formula. (ii) Write chemical equation to show its reaction with
(1) Sodium metal
(2) Excess conc. sulphuric acid
(3) Ethanoic acid in the presence of an acid catalyst
(4) Acidified potassium dichromate
Also write the name of the product formed in each case.- CBSE Class X - 2024
- Science
- Chemical Properties Of Carbon Compounds
- More than three million carbon compounds have been discovered in the field of chemistry. The diversity of these compounds is due to the capacity of carbon atoms for bonding with one another as well as with other atoms. Most of the carbon compounds are poor conductors of electricity and have low melting and boiling points.
- CBSE Class X - 2024
- Science
- Chemical Properties Of Carbon Compounds
Write notes on the following:
(a) Saturated and unsaturated hydrocarbons
(b) Corrosion
(c) Precipitation reaction- UP Board X - 2023
- Science
- Chemical Properties Of Carbon Compounds
Questions Asked in CBSE X exam
- Describe the historical factors that contributed to the emergence of nationalist tensions in the Balkans.
- CBSE Class X - 2025
- The Rise of Nationalism in Europe
Match Column-I with Column-II and choose the correct option:
Column-I (Minerals) Column-II (Features) A. Copper (i) Used in manufacturing of steel and plants B. Bauxite (ii) Used in electric and electronic industries C. Mica (iii) Used in electric cables and utensils D. Manganese (iv) Used in aluminium production Choose the correct answer from the options given below:
- CBSE Class X - 2025
- Minerals and Energy Resources
- Matilda’s character embodies the journey of change or progression throughout the story, encapsulating the transformations she endured as a consequence of her experiences, trials, and engagements with other characters.
In the light of the above information, trace the transformation seen in Matilda’s character in the story.
(The Necklace) Give reasons:
(i) The sky appears dark to passengers flying at very high altitudes.
At very high altitudes, passengers are above the atmosphere where there is less scattering of sunlight. As a result, they do not see the scattered blue light and the sky appears dark, similar to the condition experienced by astronauts in space.
(ii) 'Danger' signal lights are red in color.- CBSE Class X - 2025
- Refraction
- Imagine you are a Village Development Officer of a village. Explain the usefulness of formal sources of credit for the farmers.
- CBSE Class X - 2025
- Money and Credit
Concepts Used:
Allotropes of Carbon
The existence of a chemical element in one or more physical forms happening in the same physical state is called Allotropes or allotropy. Allotropes may show different physical or chemical states turning on the atom arrangement or the number of existent atoms. While carbon and sulfur is the common element presenting allotropy. Carbon can make further allotropes due to its five-membered valency.
Read More: Allotropes of Carbon
Allotropes of Carbon:
Carbon is part of a p-block element.
- The atomic number of carbon = 6
- It belongs to group 14.
- It makes up about 18.5% of the human body by mass.
Carbon has only two types of allotropes, such as;
- Crystalline
- Amorphous
The crystalline form of carbon consists of allotropes like;
- Diamond
- Graphite
- Fullerenes
The amorphous form of carbon consists of allotropes like;
- Coal
- Coke
- Wood charcoal
- Animal charcoal
- Lampblack
- Gas carbon