which two of the following are typical characteristics of physical change.The number of particles changesThe change can often be easily reversedThe types of particles change to form one or more new substancesThe positions or speeds of the particles change

Sure, let's analyze each characteristic step by step:

1. The number of particles changes:

   • In a physical change, the number of particles typically does not change. The particles may rearrange or change their state (e.g., from solid to liquid), but their quantity remains the same.

2. The change can often be easily reversed:

   • This is a typical characteristic of a physical change. For example, melting ice can be reversed by freezing the water back into ice.

3. The types of particles change to form one or more new substances:

   • This is a characteristic of a chemical change, not a physical change. In a chemical change, the original substances' particles change to form new substances with different properties.

4. The positions or speeds of the particles change:

   • This is a typical characteristic of a physical change. For example, in the transition from solid to liquid, the particles move more freely and their positions change.

Therefore, the two typical characteristics of a physical change are:

• The change can often be easily reversed.
• The positions or speeds of the particles change.