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Q69 (NDA-II/2009) Science & Technology › Basic Science (Physics, Chemistry, Biology) › Basic mechanics concepts Answer Verified

The density of cast iron having specific gravity 7.20 is

Result
Your answer: —  Â·  Correct: D
Explanation

Specific gravity, also known as relative density, is a dimensionless quantity defined as the ratio of the density of a substance to the density of a reference material, typically water at 4°C [t5, t6]. The density of water is approximately 1000 kg/m³ in SI units [t1, t3, t10]. To calculate the density of a substance from its specific gravity, the formula used is: Density = Specific Gravity × Density of Water [t10]. Given that the specific gravity of cast iron is 7.20 [t1, t7], its density is calculated as 7.20 × 1000 kg/m³, which equals 7200 kg/m³ [t10]. This conversion is essential in engineering and physics to express mass per unit volume in standard SI units [c1, t9]. Therefore, option 4 is the correct density for cast iron with a specific gravity of 7.20.

Sources

  1. [1] Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 9: The Amazing World of Solutes, Solvents, and Solutions > How do scientists define density? > p. 141
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SIMILAR QUESTIONS

NDA-I · 2013 · Q53 Relevance score: 1.75

Specific gravity of silver is 11 and specific gravity of iron is 8. Which one among the following is the approximate relative density of silver with respect to iron?

IAS · 2002 · Q150 Relevance score: -2.61

Assertion (A) : An iron ball floats on mercury but gets immersed in water. Reason (R) : The specific gravity of iron is more than that of mercury.

CDS-I · 2003 · Q96 Relevance score: -5.85

Consider the following forms of iron: I. Pig iron II. Wrought iron IIL Cast iron What is the sequence of these in terms of descending order of their carbon content?