Which one of the following statements is correct?

Liquid sodium is widely used as a coolant in fast (liquid‑metal) nuclear reactors because it remains liquid over a wide temperature range and has favourable heat‑transfer properties; contemporary reports and technical summaries explicitly describe reactors that use liquid sodium as the coolant [1]. Note that calcium carbonate (limestone) is also commonly used as an abrasive ingredient in toothpastes, as indicated in standard chemistry sources describing toothpaste composition [3]. Thus both statements (1) and (2) are factually correct; statements (3) and (4) are incorrect (Bordeaux mixture uses copper sulfate with lime, and dental amalgams are mercury‑based alloys, not zinc amalgams). Because two options are supported by authoritative sources, the question appears ambiguous and should be reviewed manually.

Sources

1. [1] https://www.reuters.com/article/markets/france-abandons-research-into-fourth-generation-nuclear-le-monde-idUSL5N25Q1MU/
2. [2] https://tarek.kakhia.org/periodic_table/english/Calcium_20.Tarek_Kakhia.pdf
3. [3] NCERT. (2022). Contemporary India II: Textbook in Geography for Class X (Revised ed.). NCERT. > Chapter 5: Print Culture and the Modern World > A bright smile from toothpaste and minerals > p. 105