A relative density bottle has a mass of 19 g when empty. When it is completely filled with water, its mass is 66 g. What will be its mass if completely filled with alcohol of relative density 0.8?
A
47 g
B
52.8 g
C
37.6 g
D
56.6 g
Verified Correct Answer: D.
Physical Principles & Numerical Solution
Let mb=mass of empty bottle,
\(m_w\)=mass of water only and
\(m_a\)= mass of alcohol only
given; \(m_b\)=19g
\(m_b\) + \(m_w\) = 66g
\(m_b\) + \(m_a\) = ?
R.d=0.8
R.d=mass of alcohol
⇒\(\frac{mass of alcohol}{mass of equal volume of water}\)
⇒ mass of equal volume of water = \(m_w\)=66-19=47g
⇒0.8 = \(\frac{m_a}{47}\)
⇒\(m_a\)=0.8\times47 =37.6g
; \(m_b\) + \(m_a\) = 19+37.6=56.6g
Source: WAEC / JAMB / NECO Classroom Archive (Record #68070)