For most compounds in which a nitrogen atom bears no formal charge, the valence of this nitrogen atom is

3

Explanation:

Hello,

In this case, as nitrogen is not bearing any formal charge, we apply its mathematical definition to find such oxidation state:

Formal charge= # of valence electrons - # of lone-pair electrons - 1/2 # of bond pair electrons

Since no formal charge is born, no lone-pair electrons are formed and 6 bond pair electrons are always present for the nitrogen to complete the octate, the valence turns out into:

# of valence electrons = 0 + 0 + 1/2 * 6

# of valence electrons = 3

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i believe it is 40–40–20%

explanation:

the best answer is d because the strong cohesion is caused by the ability of water molecules to undergo hydrogen bonding.

a is incorrect because when water solidifies, it becomes   ice, which expands and occupies a bigger volume for the same mass of water in its liquid state.

b is incorrect because water has high surface tension. besides bonding to itself it hydrogen bonds to other molecules at the top decreasing possibility for breaking of attractive forces.

c is incorrect because the water molecule has oxygen which is highly electronegative and so pulls the electron pair towards itself creating a dipole moment, making the molecule polar.

e is incorrect because water has strong adhesion, ability to stick to other molecules such as glass because of this molecules having stronger hydrogen bonding than water.