At $STP$,the moles of oxygen in $2.8 \ L$ of $CO_2$ gas is:

If the price of $1 \ kg$ of common salt is $7$ rupees and the price of $1 \ kg$ of sugar is $14$ rupees,then what is the cost of $1 \ mole$ of salt and sugar?

Assertion : The number of $O$ atoms in $16 \ g$ of oxygen and $16 \ g$ of ozone is same.
Reason : Each of the species represents $1 \ g$ molecule of oxygen.

What is the volume occupied by $1$ molecule of water, if its density is $1 \,g \,cm^{-3}$?

Calculate the number of molecules present in $5.4 \ g$ of urea (Molar mass of urea $= 60 \ g \ mol^{-1}$).

Among the following,choose the ones with an equal number of atoms.
$A$. $212 \ g$ of $Na_2CO_3(s)$ [molar mass $= 106 \ g/mol$]
$B$. $248 \ g$ of $Na_2O(s)$ [molar mass $= 62 \ g/mol$]
$C$. $240 \ g$ of $NaOH(s)$ [molar mass $= 40 \ g/mol$]
$D$. $12 \ g$ of $H_2(g)$ [molar mass $= 2 \ g/mol$]
$E$. $220 \ g$ of $CO_2(g)$ [molar mass $= 44 \ g/mol$]
Choose the correct answer from the options given below.