A mass of 2.72 g of an alloy containing Pb, required for dissolved in `HNO_3` containing `50%` by mass of `HNO_3`. When a `H_(2)SO_(4)` solution was added, 1.5 g of precipitate (A) appeared `H_(2)S` gas was then passed into the remaining solution a secfond precipitate was formed which when calcined in air produced 1.6 g of a compound B. Determine the composition of an alloy. (Al does not form `Al_(2)S_(3)` due to the hydrolysis of sulphide).

Explanation

To determine the composition of the alloy containing lead (Pb) and aluminum (Al), we will follow these steps:

### Step 1: Calculate the mass of lead (Pb) precipitated
When the alloy is dissolved in HNO3, Pb is converted to Pb(NO3)2. When H2SO4 is added, PbSO4 precipitates. The mass of the precipitate (A) formed is given as 1.5 g. The molar mass of PbSO4 is calculated as follows:

- Molar mass of Pb = 207.2 g/mol
- Molar mass of S = 32.07 g/mol
- Molar mass of O = 16.00 g/mol (4 O atoms)
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