Greenhouse gases are those that trap heat in Earth's atmosphere. Common ones include:
Water (H2O) in vapor form does act as a greenhouse gas, but in its pure liquid form (as stated) it's not categorized as a greenhouse gas in the same atmospheric context.
Some reactions of $NO _2$ relevant to photochemical smog formation are

Identify $A , B , X$ and $Y$
200 ml of an aqueous solution contains 3.6 g of Glucose and 1.2 g of Urea maintained at a temperature equal to 27$^{\circ}$C. What is the Osmotic pressure of the solution in atmosphere units?
Given Data R = 0.082 L atm K$^{-1}$ mol$^{-1}$
Molecular Formula: Glucose = C$_6$H$_{12}$O$_6$, Urea = NH$_2$CONH$_2$