According to the law of conservation of matter, the number of is not changed by a chemical reaction.

Answer ;

atoms

Explanation ;

The law of conservation of matter states that atoms cannot be created or destroyed by chemical reactions. Therefore, the number of atoms is not changed by a chemical reaction. However, the way the atoms are combined is changed, so the number of bonds, molecules, and products can all change.

1.solid

2.carbon dioxide

3.helium

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.