If you have chopped a lot of vegetables then there is no need to worry. You can store them in an airtight container in the refrigerator. This will prevent the chopped vegetables from coming in contact with air and prevent them from spoiling.
If you don't have an airtight container, you can wrap chopped vegetables and fruits in plastic wrap or aluminum foil. This keeps the chopped vegetables safe for several days.
Cut fruits like apple, banana and guava start changing colour when exposed to air. To deal with this, sour juice of lemon, orange etc. has to be applied on the cut part of the fruit. Applying sour juice keeps cut fruits and vegetables fresh for a long time.
Cut fruits and vegetables can be preserved for many days by keeping them in water. This trick proves to be very successful in preserving carrots and apples etc.
If you want to keep cut fruits and vegetables fresh for a longer time and you do not have a refrigerator, you can use wet paper towels. This also prevents the cut fruits and vegetables from losing moisture.