Answer:1. Add a little butter to your cupcakes.Butter: MN (mass noun, cannot be counted individually)2. A flock of birds flew back to their nests.Flock: CN (count noun, it refers to a group of birds which can be counted)3. The old man can still carry a sack of rice.Sack: CN (count noun, the sack can be counted)Rice: MN (mass noun, rice grains cannot be individually counted)4. Have you seen the liquid soap in the cabinet?Soap: MN (mass noun, liquid soap is measured, not counted)5. She needs a can of soil for her plant.Can: CN (count noun, the can can be counted)Soil: MN (mass noun, soil cannot be individually counted)