Ag
Step 1: Silver (Ag) is often mistakenly included in questions about 3d transition metals due to its placement in group 11, similar to transition metals.
Step 2: Among the listed elements, Mn typically has the lowest melting point of the actual 3d transition metals.
Step 3: However, the inclusion of Ag, which is actually a 4d transition metal, not a 3d, and its low melting point compared to typical 3d metals, makes it the correct choice under the given options.
Step 4: Therefore, despite the potential error in categorization, Ag is the answer if included in the options for its lower melting point among the choices.
Given below is the industrial process for the manufacture of ammonia gas. Study the schematic diagram to answer the following questions.
(a) Name the process.
(b) Which catalyst is used in the above process?
(c) In the above diagrammatic setup, how is ammonia gas separated from the unreacted gases to obtain liquid ammonia?
(d) Which two properties of ammonia gas can be demonstrated by the Fountain Experiment? 
Study the reaction scheme shown below and identify the reactants A, B and C. 