A metal salt MX when exposed to light splits up to form metal M and a gas X₂. Metal M is used in making ornaments whereas gas X₂ is used in making bleaching powder. The salt MX is itself used in black and white photography.

• a) What do you think metal M is?
• b) What could be gas X₂?
• c) Name the metal salt MX.
• d) Name any two salt solutions which on mixing together can produce a precipitate of salt MX.
• e) What type of chemical reaction takes place when salt MX is exposed to light? Write the equation of the reaction.

The scenario describes a metal salt MX that decomposes upon exposure to light, producing metal M and gas X₂. Let's break down the questions one by one.

Identifying Metal M

Metal M is likely to be silver (Ag), as it is commonly used in making ornaments.

Determining Gas X₂

Gas X₂ is probably chlorine (Cl₂), which is used in the production of bleaching powder.

Naming the Metal Salt MX

The metal salt MX is likely silver chloride (AgCl), as it fits the description of being used in black and white photography.

Producing Salt MX Through Mixing

Two salt solutions that can produce a precipitate of salt MX (silver chloride) when mixed are:

• Sodium chloride (NaCl)
• Silver nitrate (AgNO₃)

Type of Reaction and Equation

The reaction that occurs when salt MX is exposed to light is a decomposition reaction. The equation for this reaction is:

2 AgCl (s) → 2 Ag (s) + Cl₂ (g)