B is the correct answer for it
Answer:
C 16
Explanation:
Since there are 6 valence electrons, this belongs in the same column as Oxygen. In fact, this is a diagram of a neutral oxygen atom with 8 total electrons.
Balancing of chemical equation is essential because of the law of conservation of mass, which states that the mass of a system can not be created or removed.
The second equation is balanced
This is because the number of elements of each atom in the product side equal the number of elements of each atom on the reactant side.
The first equation is not balanced

This is because there is 1 molecule of
on reactant side as compared to 3 molecules of 
To balance the equation we add a coefficient of 3 on sulphuric acid (
) and a coefficient of 3 on hydrogen (
)

Answer:
is to examine that whether the other variables causes a change in another. The experimental setup of controlled experiments are designed to test the hypotheses. ... It allows to change more than one variable, on the condition that all other variables are controlled.