Question

Arrange the following building materials in the increasing order of density of materials :
A. Granite
B. River sand
C. Water
D. Steel
Choose the correct answer from the options given below:

• A. B < A < D < C
• B. C < B < A < D
• C. C < B < D < A
• D. C < D < B < A

Hint:

A useful rule of thumb: Metals > Stones > Loose Soils > Liquids.

Answer 1

The Correct Option is B

Concept: Density is the mass per unit volume of a substance ($\rho = m/V$). In civil engineering, knowing the relative densities is crucial for calculating dead loads.

Step 1: Identifying the baseline (Water).
Water is the standard reference. Its density is approximately $1000 \text{ kg/m}^3$. This is the lowest density in the list. Therefore, C is first.

Step 2: Comparing Sand and Stone.
River sand is a granular material with air voids between particles. Its bulk density is typically around $1450 - 1600 \text{ kg/m}^3$. Granite, being a solid igneous rock, is much denser, typically around $2600 - 2700 \text{ kg/m}^3$. Therefore, B (Sand) is lighter than A (Granite).

Step 3: Identifying the heaviest material (Steel).
Steel is a dense metal alloy. Its standard density used in engineering calculations is $7850 \text{ kg/m}^3$. This is significantly higher than any stone or water. Therefore, D is last.

Step 4: Final Order.
The increasing order of density is: Water (1000) < River sand ($\approx 1600$) < Granite ($\approx 2650$) < Steel (7850). This corresponds to C < B < A < D.