What is the volume (in litres) of oxygen at $STP$ required for complete combustion of $32 \,g$ of $CH_4$? (Molecular weight of $CH_4$ is $16$)

How many grams of $3-$hydroxypropanal $(MW=74)$ must be dehydrated to produce $7.8 \ g$ of acrolein $(MW=56)$ $(C_3H_4O)$ if the percentage yield is $64\%$? (Round off to the nearest integer).
[Given: Atomic masses: $C = 12.0 \ u, H = 1.0 \ u, O = 16.0 \ u$]

What is the value of $w$ (mass of solute in grams) required to prepare a definite volume of a standard solution of known normality $(N)$?
[$N = \text{normality}$,$E = \text{equivalent weight}$,$V = \text{volume of solution in } mL$]

$100 \ mL$ of $0.1 \ N$ hypo solution is decolourised by the iodine liberated from the addition of $x \ g$ of crystalline copper sulphate to an excess of $KI$. The value of $x$ is ............. $g$ (molecular weight of $CuSO_4 \cdot 5H_2O$ is $250$).

$1.25 \ g$ of a solid dibasic acid is completely neutralized by $25 \ mL$ of $0.25 \ M$ $Ba(OH)_2$ solution. The molecular mass of the acid is:

Sulfur trioxide is prepared by the following reactions:
$S_{8(s)} + 8O_{2(g)} \to 8SO_{2(g)}$
$2SO_{2(g)} + O_{2(g)} \to 2SO_{3(g)}$
How many grams of $SO_3$ are obtained from $1 \ mol$ of $S_8$?