Answer: The staircase is 14.28 m high.
Explanation:
Given : Mass = 0.1 kg
Potential energy = 14 J
Potential energy is the energy occupied by the position of a substance. Therefore, formula for potential energy is as follows.
P.E = mgh
where,
m = mass
g = gravitational energy = 
h = height of object
Substitute the values into above formula as follows.

Thus, we can conclude that the staircase is 14.28 m high.
Answer:
The correct answer would be - observing with the help of five senses.
Explanation:
To find and describe the physical properties of the given substance or the solution or liquid students can observe using their five senses. By looking at the liquid one can find its state and color, by smelling students can find the odor of the sample, by touching it one can observe and describe the texture.
Fluidity can also be measure by the touch if the solution is viscous or free-floating. By using a thermometer and using a graduated cylinder one can find the temperature at room temperature and the weight of substance respectively.
Answer: mole
A formula unit represents the simplest ratio of elements in a mole of an ionic compound.
Explanation:
The formula unit, also known as the empirical formula, gives the simplest whole number ratio of the components of the elements in a mole of an ionic compound.
Thus, the formula unit and the molecular formula of a compound can be the same.
For example: Glucose with C6H12O6 will have a formula unit of CH2O. Thus, the simplest ratio of carbon, hydrogen and oxygen in glucose is 1:2:1