How many moles of potassium chlorate need to be heated to produce $5.6 \, L$ of oxygen at $STP$?

Element $A$ reacts with oxygen to form a compound $A_2O_3$. If $0.359 \ g$ of $A$ reacts to form $0.559 \ g$ of the compound,the atomic mass of $A$ is:

What mass of $95 \%$ pure $CaCO_3$ will be required to neutralise $50 \ mL$ of $0.5 \ M \ HCl$ solution according to the following reaction? (In $g$)
$CaCO_{3(s)} + 2HCl_{(aq)} \rightarrow CaCl_{2(aq)} + CO_{2(g)} + H_2O_{(l)}$
[Calculate up to the second decimal place]

$0.092 \ g$ of a compound with the molecular formula $C_3H_8O_3$ on reaction with an excess of $CH_3MgI$ gives $67.00 \ mL$ of methane at $STP$. The number of active hydrogen atoms present in a molecule of the compound is

$A$ bottle of cold drink contains $200 \, mL$ of liquid with $0.1 \, M$ $CO_2$. If $CO_2$ behaves ideally,what will be the volume of $CO_2$ gas at $STP$ in the cold drink solution (in $, L$)?

$23 \ g$ of $Na$ metal reacts with ethanol to produce which of the following?