Saurabh Jha

(a) The law that is followed by balancing a chemical equation is the Law of Conservation of Mass. According to this law, matter is neither created nor destroyed in a chemical reaction. Therefore, the number of atoms of each element must be the same on both sides of a balanced chemical equation.

(b) Let's balance the given chemical equation:

Here's the balanced equation:

In this balanced equation, the number of atoms for each element (Na, H, O) is the same on both sides, satisfying the Law of Conservation of Mass.

The gravitational force does not have its own unit of work. Work is generally measured in joules (J) in the International System of Units (SI). When an object is moved against the force of gravity, the work done is given by the formula:

\[ \text{Work} = \text{Force} \times \text{Distance} \times \cos(\theta) \]

where:
- \(\text{Force}\) is the force applied (in newtons, N),
- \(\text{Distance}\) is the distance over which the force is applied (in meters, m), and
- \(\theta\) is the angle between the force vector and the direction of motion.

In the case of gravitational force near the Earth's surface, the force can be given by \( \text{Force} = m \times g \), where \( m \) is the mass of the object and \( g \) is the acceleration due to gravity (approximately 9.8 m/s² on the surface of the Earth).