Is it white metal or chrome?

The supports are made of shiny lightweight metal and the shelves are fiberboard.

Can the rack stand on an area that is half carpet and half floor. Or would it cause it to not be steady.

Just put some cardboard under the legs on the bare floor in order to level it.

YAHEETECH ‎YT-00093881 5-Tier Metal Garage Shelves Steel Storage Rack Shelf - Use Manual - Use Guide PDF.
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Table of contents

User Manual Home Organization Furniture Unit

Please carefully read the instructions and caution warnings listed below before use. Following this guide will ensure that you install, use and maintain the product properly.
It is recommended that you keep this installation and user instructions for future reference use.
Never allow children to climb the product. Take special safety measures when you have children around.
Be sure to check if the product is intact after you open the package. Do not use it if there are serious damages such as cracks or bends.
Do not overload the product.Improper loading can cause serious damages to it and/or injury to the user.
Do not turn the product upside down, on its side, or at an angle off level. Only use it in an upright position on a flat, level surface.
Do not place the product near flammable gas or combustibles or heat sources such as gasoline, benzene, ovens, grills, etc.
Use gloves for safety care for your hands during the installation.
Do not use sharp instruments, rubbing alcohol, corrosive chemicals, or abrasive cleaners to clean the product.