Question

Hydrogen is not obtained when sodium reacts with:

• A. cold water
• B. dilute $H_2{SO}_4$
• C. molten NaCl
• D. dilute HCl

Answer 1

Answer: (C)

molten NaCl

• When sodium is dropped in cold water, it reacts explosively and burns with a golden-yellow flame. It forms sodium hydroxide with the liberation of hydrogen gas.
  

Na + H₂O → Na(OH)₂ + H₂

• Sodium reacts with sulphuric acid to produce sodium sulphate and hydrogen.
  

Na + H₂SO₄ → Na₂SO₄ + H₂

• Molten NaCl on reaction with sodium doesn't produce H₂. However, molten sodium chloride can be electrolysed to produce sodium metal and chlorine gas.
  

• Sodium reacts with hydrochloric acid to produce sodium chloride and hydrogen.
  

Na + HCl → NaCl + H₂

Hence, option C is correct.