Questions

A concentrated solution will contain the most solute molecules per solvent molecules.

Here in the given options,

1)  6/10 = 0.6

2) 20.5/50 = 0.41

3) 30/120 = 0.25

4) 2.6/2 = 1.3

Hence, option D) is most concentrated.

$$\begin{gathered} 1936 + 529 = ?2 + 256 \\ 2465 = ?2 + 256 \\ ?2 = 2465 - 256 \\ ?2 = 2209 \\ ?=47 \end{gathered}$$

NH3, Ammonia is a neutral compound as the individual oxidation numbers elements that make up the compound NH3 are Nitrogen (N) and Hydrogen (H) sum to zero. 

We do not speak of the oxidation number of a molecule. We can speak of the oxidation numbers of the individual elements that make up the compound.

Here the oxidation number of Nirogen is -3 and that of Hydrogen is +1.

Now, NH3 = 1(-3) + 3(+1) = -3 + 3 = 0.

A book has a spine to hold all the pages, but it has no bones.