Metres squared (example: 40m2) or Square feet (40 sq.ft or 40 ft2) or Square yards (12 sq yds or 12 yds2). It will also depend on the surface being painted. Raw or rough surfaces require more paint.
You have not specified the quantity of water. You cannot measure one fifth of an unspecified quantity.
The answer will depend on what quantity is being measured. Since that has not been specified, there can be no sensible answer.
Not Otherwise Specified
Material measure refers to the physical quantity of an item being measured, usually by weight or volume. It is crucial for inventory management and tracking the amount of a particular material on hand.
The measure of the amount of an object or material is its quantity, which can be expressed in terms of weight, volume, length, or other appropriate units of measurement. The specific unit of measure used depends on the characteristics and properties of the object or material being quantified.
The amount of material in a substance is its mass. Mass is a measure of the quantity of matter in an object and is typically measured in units such as grams or kilograms.
Resistivity is a scalar quantity. It is a measure of how strongly a material opposes the flow of electric current through it.
Stress is a physical quantity that represents the internal response of a material to an external force. It is typically described in terms of force per unit area and is a measure of how much deformation a material undergoes when subjected to external loading.
Scalar quantity, e.g, mass, speed of light, charge, etc.
What can measure only one quantity of liquid?
The term that describes the quantity of matter in an object is "mass." Mass is a measure of the amount of material in an object and is typically measured in units such as kilograms or grams.
The measure of how much material an object contains is known as its volume. Volume is typically measured in cubic units such as cubic meters or cubic centimeters, depending on the size of the object being measured.