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Science · 2024 · 3 marks
CBSE 2024 · Region 4 · Set 1 · Q27
Write the common name and the chemical name of the compound $\displaystyle \mathrm{CaSO}_{4} \cdot \frac{1}{2} \mathrm{H}_{2} \mathrm{O}$. Write the method of its preparation. Give chemical equation for the reaction, when water reacts with $\displaystyle \mathrm{CaSO}_{4} \cdot \frac{1}{2} \mathrm{H}_{2} \mathrm{O}$.
Marking-scheme solution
Plaster of Paris; Calcium sulphate hemihydrate
-Prepared from gypsum \(\displaystyle \left(\mathrm{CaSO}_{4} \cdot 2 \mathrm{H}_{2} \mathrm{O}\right)\) by heating it at 373K
\[\mathrm{CaSO}_{4} \cdot \frac{1}{2} \mathrm{H}_{2} \mathrm{O}+1 \frac{1}{2} \mathrm{H}_{2} \mathrm{O} \longrightarrow \mathrm{CaSO}_{4} \cdot 2 \mathrm{H}_{2} \mathrm{O}
\]
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CBSE Class 10 Science past-paper question from the 2024board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.