Which of the following is unbalanced A. SnO2 + H2 → Sn + 2 H2O
B. 2Na + 2H2O → 2NaOH + H2
C. N2O5 + H2O → HNO3
D. 2Fe + 3Cl2 → 2FeCl3

The unbalanced chemical equation is;

C. N₂O₅ + H₂O → HNO₃

Explanation:

In balancing a chemical reaction equation, only the coefficients of the terms of the reactants and/or the products are adjusted (and not the subscripts to the atoms in the compounds) to ensure that the total number of each element is the same on either side of the arrow for the chemical reaction

A coefficient term is the number multiplier of the compounds and elements in a chemical reaction

Therefore, the balanced chemical equation is obtained by changing the coefficient of the product from the implied '1' to a '2' as follows;

N₂O₅ + H₂O → 2HNO₃

d.) circle motion requires a force to give it a centripetal acceleration.

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.