Which of the following chemical equations proves that the law of conservation of mass is in effect? Question 2 options:

Mg2 + LiBr ---> LiMg + Br

2KCl + F2 ---> 2KF + Cl2

Na +O2 ---> Na2O

H20 ---> H2 + O2

2KCl + F₂   →     2KF + Cl₂

Explanation:

Law of conservation of mass:

According to the law of conservation mass, mass can neither be created nor destroyed in a chemical equation.

This law was given by French chemist  Antoine Lavoisier in 1789. According to this law mass of reactant and mass of product must be equal, because masses are not created or destroyed in a chemical reaction.

For example:

2KCl + F₂   →     2KF + Cl₂

In this equation mass of reactant and product is equal. There are 2 potassium 2 chlorine and fluorine atoms on both side of equation it means mass remain conserved.

All other options are incorrect because mass is not conserved.

since the atomic number is the number of protons in the nucleus, as we move to the left on the periodic table, the electrostatic pull between the nucleus and the valence electron shell decreases. as we move down a group (vertical column), the valence shell energy level gets further and further from the nucleus.

they are made of gases.

they have a spherical shape.

they make energy through fusion.