PYQ Vault
EbooksTutor

Plaster of Paris from gypsum

This type of question, asked 3 times: 2023, 2024, 2026. All 4 questions below, oldest first.

Try each one first, then open its answer.

  1. Question 1

    2023

    28 (a)
    (i) What property do acids and bases have in common ? Explain it with an example. (ii) A compound which is prepared from gypsum has the property of hardening when mixed with water. Identify the compound and write its formula. How is this compound prepared ? Describe it in the form of a chemical equation only.

  2. Question 2

    2023

    21 (a)
    On heating ‘X’ at 373 K, it loses water molecules and becomes ‘Y’. ‘Y’ is a substance which doctors use for supporting fractured bones in the right position. (i) Identify ‘X’ and ‘Y’. (ii) How can ‘X’ be reobtained from ‘Y’ ?

  3. Question 3

    2024

    27
    Write the common name and the chemical name of the compound CaSO4⋅12 H2O\mathrm{CaSO_4 \cdot \frac{1}{2}\,H_2O}. Write the method of its preparation. Give chemical equation for the reaction, when water reacts with CaSO4⋅12 H2O\mathrm{CaSO_4 \cdot \frac{1}{2}\,H_2O}.

  4. Question 4

    2026

    25
    (a) A compound ‘A’ is used in soda-lime fire-extinguisher and decomposes on heating to form compound ‘B’. Compound ‘B’ is used for removing permanent hardness of water. Identify ‘A’ and ‘B’. (b) Write chemical formula of Plaster of Paris. At what temperature gypsum is heated to obtain Plaster of Paris ?