ANS:A - chloride

Fertiliser produced during soda ash manufacture by dual process is ammonium nitrate. Explanation:

1. Dual Process: The dual process for soda ash manufacture involves two main steps: the Solvay process and the ammonia-soda process. In the ammonia-soda process, also known as the Hou process, ammonia (NH3) is used along with sodium chloride (NaCl) and limestone (CaCO3) to produce soda ash (Na2CO3).
2. Ammonium Nitrate: During the ammonia-soda process, one of the by-products formed is ammonium nitrate (NH4NO3). This occurs when ammonia (NH3) reacts with nitric acid (HNO3), which is a component in the overall chemical reactions taking place.
3. Fertiliser Production: Ammonium nitrate is a well-known fertiliser commonly used in agriculture due to its high nitrogen content. It provides readily available nitrogen to plants, promoting their growth and development.
4. By-Product Utilisation: The production of ammonium nitrate as a by-product during the soda ash manufacturing process offers a way to utilise nitrogen-containing compounds that would otherwise be wasted. It adds value to the overall process and contributes to the sustainability of chemical manufacturing operations.
5. Other By-Products: While ammonium nitrate is produced during the ammonia-soda process, other by-products such as ammonium chloride (NH4Cl) and ammonium sulphate ((NH4)2SO4) may also be formed depending on specific reaction conditions and the composition of raw materials.