Soap is not suitable for washing in hard water because it forms:
A. Insoluble calcium and magnesium salts (scum)
B. Micelles
C. Soluble sodium salts
D. Foam
Answer: Option A
Solution (By JKExamLibrary)
Soap (sodium carboxylate) reacts with Ca²⁺ and Mg²⁺ ions present in hard water to form an insoluble precipitate known as scum. This reduces lathering and wastage of soap. Synthetic detergents do not form scum because their calcium/magnesium salts are soluble.
Explanation:
The thermite process involves the reduction of a metal oxide by aluminum powder, which is highly exothermic. It is used to extract metals like chromium, manganese, and iron from their oxides (e.g., Cr2O3 + 2Al -> 2Cr + Al2O3). It is also practically used for welding iron railway tracks.
Explanation:
Fossil fuels (coal, petroleum, natural gas) are formed from organic matter deposited in sedimentary layers, subjected to heat and pressure over geological timescales. They are non-renewable because their formation takes millions of years.
Explanation:
Isobars are atoms of different elements with the same mass number but different atomic numbers. Argon (Z=18) and Calcium (Z=20) both have a mass number of 40, making them isobars. Options A, B, and D are isotopes, as they represent the same element with different mass numbers.
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