Find the number of electrons present in $34 \ g$ of $NH_{3(g)}$. (Express your answer in terms of $N_A$)

The mass of $112 \ cm^3$ of $NH_3$ gas at $STP$ is (in $g$)

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.

$A$ thin layer of cobalt is deposited on a plate with a total area of $0.5 \ m^2$ and a thickness of $0.005 \ cm$. How many cobalt atoms are deposited on the plate? (Density of cobalt $= 8.9 \ g \ cm^{-3}$,Atomic mass of $Co = 59 \ g \ mol^{-1}$)

What is the value of Avogadro's number?

Which of the following has the greatest number of atoms?