Iron sulphide is heated in air to form $A$, an oxide of sulphur. $A$ is dissolved in water to give an acid. The basicity of this acid is:

Iron sulphide is heated in air to form $A$,an oxide of sulphur. $A$ is dissolved in water to give an acid. The basicity of this acid is

$1 \, L$ aqueous solution of $H_{2}SO_{4}$ contains $0.02 \, mmol$ of $H_{2}SO_{4}$. $50 \%$ of this solution is taken and diluted with deionized water to give $1 \, L$ solution $(A)$. In solution $(A)$, $0.01 \, mmol$ of $H_{2}SO_{4}$ is added. The total amount of $H_{2}SO_{4}$ in the final solution is $x \times 10^{-3} \, mmol$. The value of $x$ is:

Which of the following species has the highest mass?

The incorrect postulates of the Dalton's atomic theory are :
$A$. Atoms of different elements differ in mass.
$B$. Matter consists of divisible atoms.
$C$. Compounds are formed when atoms of different element combine in a fixed ratio.
$D$. All the atoms of given element have different properties including mass.
$E$. Chemical reactions involve reorganisation of atoms.
Choose the correct answer from the options given below :

Assign $A$,$B$,$C$,$D$ from the given type of reaction.
$2AgF + MgCl_2 \longrightarrow MgF_2 \downarrow + 2AgCl \downarrow$