Particles of the substance have the most kinetic energy when the substance is(a)1. A gas. The part of the graph that represents where the substance has the least amount of potential energy is labeled(b)1. Solid.
Gas molecules have the highest average velocities among the three states of matter so gas has the highest kinetic energy. During freezing, a substance loses a lot of potential energy so solid has the least potential energy.
The Correct Answer Is 3.2
Answer:

Explanation:
Given that:
Half life = 30 min
Where, k is rate constant
So,
The rate constant, k = 0.0231 min⁻¹
Using integrated rate law for first order kinetics as:
Where,
is the concentration at time t
is the initial concentration
Given that:
The rate constant, k = 0.0231 min⁻¹
Initial concentration
= 7.50 mg
Final concentration
= 0.25 mg
Time = ?
Applying in the above equation, we get that:-
