agar is the solidifying agent
solidifying agent.
lactose in MacConkey agar helps to distinguish between lactose fermenters and lactose non -fermenters. it makes the medium selective for lactose fermenters.
no because it is gram positive and MacConkey agar does not allow growth of most gram positive bacteria due to presence of crystal violet
Yes. But because it is not a lactose fermenter, the colonies will be colorless (or sometimes have a green tint).