Final answer:
The nonspontaneous processes among the given options are a) a bike going up a hill and c) obtaining hydrogen gas from liquid water, as both require an external source of energy to occur.
Step-by-step explanation:
The student has asked which of the following processes are nonspontaneous: a) a bike going up a hill, b) a meteor falling to Earth, c) obtaining hydrogen gas from liquid water, d) a ball rolling down a hill. To answer this, we must understand the concept of spontaneous and nonspontaneous processes. A spontaneous process is one that occurs naturally under certain conditions without the need for external energy input. In contrast, a nonspontaneous process requires the continual input of energy to occur.
Given this definition:
- (a) A bike going up a hill is a nonspontaneous process because it requires external energy input, namely from a person or a motor.
- (b) A meteor falling to Earth is a spontaneous process as it happens due to the natural gravitational attraction of the Earth without the need for an external energy source.
- (c) Obtaining hydrogen gas from liquid water is generally a nonspontaneous process because it typically requires an external energy source, such as electricity, to induce electrolysis.
- (d) A ball rolling down a hill is a spontaneous process as it occurs naturally due to gravitational force without requiring additional energy.