Which one of the following is the lightest?

Chlorophyll extracted from the crushed green leaves was dissolved in water to make $2 \, L$ solution of $Mg$ of concentration $48 \, ppm$. The number of atoms of $Mg$ in this solution is $x \times 10^{20}$ atoms. The value of $x$ is (Nearest Integer) (Given : Atomic mass of $Mg$ is $24 \, g \, mol^{-1}$,$N_{A} = 6.02 \times 10^{23} \, mol^{-1}$)

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

Assign $A, B, C, D$ from the given type of reaction.
$CaCl_2 + Na_2SO_4 \longrightarrow $ No reaction

How many moles of aluminum oxide $(Al_2O_3)$ are produced when $1 \text{ mole}$ of potassium chlorate $(KClO_3)$ undergoes thermal decomposition,and the resulting gaseous product is reacted with excess aluminum?

State whether the following statements are true or false:
$(i)$ $^\circ F = \frac{9}{5} (^\circ C) + 32$
$(ii)$ In $1808$,Dalton published the law of chemical combination in the journal "New System of Chemical Philosophy".
$(iii)$ If the molar mass of a dibasic acid is $100$,its equivalent mass is $200$.