Chemical Reactions

Step 1: Reaction Analysis
This is a disproportionation reaction of sulfur in hot concentrated alkali.
Step 2: Equation
The balanced chemical equation is: $ Na_{2}SO_{3}$).
Final Answer: (B)

Step 1: Reaction
reacts with acidified potassium dichromate ( ).
Step 2: Product
The reaction produces chromium pentoxide ( ), also known as chromic peroxide. $ CrO_{5}$ has a deep blue colour in ethereal solution but is unstable.
Final Answer: (C)

Step 1: Reaction Type
Concentrated acts as a strong dehydrating agent.
Step 2: Equation
Heating oxalic acid results in its dehydration:
Step 3: Conclusion
The gaseous products are carbon monoxide and carbon dioxide.
Final Answer: (B)