✓ Board-verified↻ asked 3×
Science · 2026 · 3 marks
CBSE 2026 · Region 5 · Set 1 · Q27
(a)Give the chemical name and formula of Plaster of Paris.(b)Write the chemical equation of its preparation.(c)Give any two uses of it.(a)Name the acid present in ant's sting.(b)Give reason :(i)While diluting an acid, it is recommended that the acid should be added to water.(ii)Baking soda is used as an antacid.
(a)
Give the chemical name and formula of Plaster of Paris.
(b)
Write the chemical equation of its preparation.
(c)
Give any two uses of it.
(a)
Name the acid present in ant's sting.
(b)
Give reason :
(i)
While diluting an acid, it is recommended that the acid should be added to water.
(ii)
Baking soda is used as an antacid.
Marking-scheme solution
(a)
Calcium sulphate hemihydrate
$\displaystyle \mathrm{CaSO}_{4} \cdot \frac{1}{2} \mathrm{H}_{2} \mathrm{O}$
(b)
$\displaystyle \mathrm{CaSO}_{4} \cdot 2 \mathrm{H}_{2} \mathrm{O} \xrightarrow{373 \mathrm{~K}} \mathrm{CaSO}_{4} \cdot \frac{1}{2} \mathrm{H}_{2} \mathrm{O}+\frac{3}{2} \mathrm{H}_{2} \mathrm{O}$
(c)
Plaster of Paris is used for
making toys
to support fractured bones in right position.
(a)
Methanoic acid/ Formic acid/ HCOOH.
(b)(i)
When acid is added to water, it does not cause excessive local heating/ does not cause splash out and burns.
(ii)
Baking soda, being alkaline in nature, neutralises excess acid in stomach and provides relief.
More from Acids, Bases and Salts
- Assertion: Concentrated nitric acid is diluted by adding water slowly to acid with constant stirring. Reason…2025 · asked 3×
- An aqueous solution turns red litmus blue. Excess addition of which of the following solution would reverse…2026 · asked 3×
- (i) A compound 'X' which is prepared from gypsum has the property of hardening when mixed with proper…2023 · asked 3×
- Which of the given option represents a family of salts?2025 · asked 3×
- Select a pair of natural indicator from the following:2024 · asked 3×
- In order to prepare dry hydrogen chloride gas in humid atmosphere the gas produced is passed through a guard…2025 · asked 3×
- Acid-base indicators can be used to distinguish between an acid and a base. Universal indicator, a mixture of…2025 · asked 3×
- Consider the following reactions: (i) Dilute hydrochloric acid reacts with sodium hydroxide. (ii) Magnesium…2025 · asked 3×
CBSE Class 10 Science past-paper question from the 2026board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.