Answer:
c. A number and a unit
Explanation:
A scalar is a real number. We often use the term scalar in the context of vectors or matrices, to stress that a variable such as a is just a real number and not a vector or matrix.
Answer:
The gauge pressure is 
Explanation:
From the question we are told that
The height of the water contained is 
The height of liquid in the cylinder is 
At the bottom of the cylinder the gauge pressure is mathematically represented as

Where
is the pressure of water which is mathematically represented as

Now
is the density of water with a constant values of 
substituting values


While
is the pressure of oil which is mathematically represented as

Where
is the density of oil with a constant value

substituting values


Therefore


The answer is number two, number four, and number one
Flame of fire could get put out with water