A Snowy Globe

First of all, I want to make it known that I have never seen a real snowball, or snowfall for that matter, being in a tropical country like India.

Molecular mass of $H_2O$ is 18 u . Therefore, one mole of $H_2O$ containing $6.022 \times 10^{23}$ molecules weighs 18 g.

I guessed there might be some 180 grams of water in a snowball. (Why 180? Just because it makes the calculations easier).

So, there are 10 moles of $H_2O$ in 180 g of snowball. The number of molecules in 10 moles of anything is $6.022 \times 10^{24}$ which means order of magnitude is $\boxed{25}$

The problem being extremely ambiguous so I guessed. The order of magnitude of Avogadro's number is $23$ . Assuming a snowball is around $100$ grams this means the order of magnitude is $\boxed{25}$ .