One atom of an element weighs $3.32 \times 10^{-23} \ g$. How many gram atoms are there in $20 \ kg$ of the element?

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?

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

$A$ flask contains $98 \ mg$ of $H_2SO_4$. If $3.01 \times 10^{20}$ molecules of $H_2SO_4$ are removed from the flask,the number of moles of $H_2SO_4$ remaining in the flask is $\left(N_A = 6.02 \times 10^{23}\right)$

The highest number of helium atoms is in

$10 \ g$ each of $CO_2$,$NH_3$,and $O_2$ were taken in three separate flasks. What is the correct decreasing order of the number of atoms?