NEET Exam  >  NEET Questions  >   The height of a mercury barometer is 75 cm a... Start Learning for Free
The height of a mercury barometer is 75 cm at sea level and 50 cm at the top of a hill. The ratio of density of mercury to that of air is 104. The height of the hill is:
  • a)
    250 m
  • b)
    2.5 km
  • c)
    1.25 km
  • d)
    750 m
Correct answer is option 'B'. Can you explain this answer?
Most Upvoted Answer
The height of a mercury barometer is 75 cm at sea level and 50 cm at ...
Given:
The height of a mercury barometer is 75 cm at sea level and 50 cm at the top of a hill.
The ratio of density of mercury to that of air is 104.

To find:
The height of the hill.

Solution:
Let's assume:
h = height of the hill (in meters)
P₁ = pressure at sea level (in pascal)
P₂ = pressure at the top of the hill (in pascal)
ρ₁ = density of air at sea level (in kg/m³)
ρ₂ = density of air at the top of the hill (in kg/m³)

Using barometric formula:
The barometric formula relates the pressure and density of the air at different altitudes.
It states that the pressure decreases exponentially with increasing altitude.

ΔP = P₂ - P₁ = -ρ₁ * g * Δh

where,
ΔP = change in pressure (in pascal)
g = acceleration due to gravity (9.8 m/s²)
Δh = change in height (in meters)

Substituting the given values:
h = 75 cm = 0.75 m (at sea level)
P₁ = atmospheric pressure at sea level = 1 atm = 1.01325 * 10⁵ Pa
ρ₁ = density of air at sea level
ρ₂ = ?

Calculating ρ₁:
ρ₁ = P₁ / (R * T)
where,
R = gas constant for air (287 J/(kg·K))
T = temperature (assumed to be constant)

Calculating ρ₂:
ρ₂ = (ρ₁ * P₂) / P₁
= (ρ₁ * (P₁ + ΔP)) / P₁
= (ρ₁ * (P₁ - ρ₁ * g * Δh)) / P₁
= ρ₁ - ρ₁² * g * Δh / P₁

Given that the ratio of density of mercury to that of air is 104:
ρ₁ / ρ₂ = 104
ρ₂ = ρ₁ / 104

Substituting the values of ρ₂ and ρ₁:
ρ₂ = ρ₁ - ρ₁² * g * Δh / P₁
ρ₁ / 104 = ρ₁ - ρ₁² * g * Δh / P₁

Calculating Δh:
Δh = (104 * P₁) / (ρ₁ * g) - 1

Substituting the given values of P₁ and ρ₁:
Δh = (104 * 1.01325 * 10⁵) / (ρ₁ * g) - 1

Calculating the value of Δh:
Δh = 2.5 km

Therefore, the height of the hill is 2.5 km.
Free Test
Community Answer
The height of a mercury barometer is 75 cm at sea level and 50 cm at ...
Difference of pressure between sea level and top of hill
∆P = (h1 - h2) × ρHg × g = (75 - 50) × 10-2 × ρHg × g …(i)
and pressure difference due to h meter of air
∆P = h × ρair × g …(ii)
By equating (i) and (ii) we get
h × ρair × g = (75 − 50) × 10−2 × ρHg × g
Height of the hill = 2.5 km.
Attention NEET Students!
To make sure you are not studying endlessly, EduRev has designed NEET study material, with Structured Courses, Videos, & Test Series. Plus get personalized analysis, doubt solving and improvement plans to achieve a great score in NEET.
Explore Courses for NEET exam

Top Courses for NEET

The height of a mercury barometer is 75 cm at sea level and 50 cm at the top of a hill. The ratio of density of mercury to that of air is 104. The height of the hill is:a)250 mb)2.5 kmc)1.25 kmd)750 mCorrect answer is option 'B'. Can you explain this answer?
Question Description
The height of a mercury barometer is 75 cm at sea level and 50 cm at the top of a hill. The ratio of density of mercury to that of air is 104. The height of the hill is:a)250 mb)2.5 kmc)1.25 kmd)750 mCorrect answer is option 'B'. Can you explain this answer? for NEET 2024 is part of NEET preparation. The Question and answers have been prepared according to the NEET exam syllabus. Information about The height of a mercury barometer is 75 cm at sea level and 50 cm at the top of a hill. The ratio of density of mercury to that of air is 104. The height of the hill is:a)250 mb)2.5 kmc)1.25 kmd)750 mCorrect answer is option 'B'. Can you explain this answer? covers all topics & solutions for NEET 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for The height of a mercury barometer is 75 cm at sea level and 50 cm at the top of a hill. The ratio of density of mercury to that of air is 104. The height of the hill is:a)250 mb)2.5 kmc)1.25 kmd)750 mCorrect answer is option 'B'. Can you explain this answer?.
Solutions for The height of a mercury barometer is 75 cm at sea level and 50 cm at the top of a hill. The ratio of density of mercury to that of air is 104. The height of the hill is:a)250 mb)2.5 kmc)1.25 kmd)750 mCorrect answer is option 'B'. Can you explain this answer? in English & in Hindi are available as part of our courses for NEET. Download more important topics, notes, lectures and mock test series for NEET Exam by signing up for free.
Here you can find the meaning of The height of a mercury barometer is 75 cm at sea level and 50 cm at the top of a hill. The ratio of density of mercury to that of air is 104. The height of the hill is:a)250 mb)2.5 kmc)1.25 kmd)750 mCorrect answer is option 'B'. Can you explain this answer? defined & explained in the simplest way possible. Besides giving the explanation of The height of a mercury barometer is 75 cm at sea level and 50 cm at the top of a hill. The ratio of density of mercury to that of air is 104. The height of the hill is:a)250 mb)2.5 kmc)1.25 kmd)750 mCorrect answer is option 'B'. Can you explain this answer?, a detailed solution for The height of a mercury barometer is 75 cm at sea level and 50 cm at the top of a hill. The ratio of density of mercury to that of air is 104. The height of the hill is:a)250 mb)2.5 kmc)1.25 kmd)750 mCorrect answer is option 'B'. Can you explain this answer? has been provided alongside types of The height of a mercury barometer is 75 cm at sea level and 50 cm at the top of a hill. The ratio of density of mercury to that of air is 104. The height of the hill is:a)250 mb)2.5 kmc)1.25 kmd)750 mCorrect answer is option 'B'. Can you explain this answer? theory, EduRev gives you an ample number of questions to practice The height of a mercury barometer is 75 cm at sea level and 50 cm at the top of a hill. The ratio of density of mercury to that of air is 104. The height of the hill is:a)250 mb)2.5 kmc)1.25 kmd)750 mCorrect answer is option 'B'. Can you explain this answer? tests, examples and also practice NEET tests.
Explore Courses for NEET exam

Top Courses for NEET

Explore Courses
Signup for Free!
Signup to see your scores go up within 7 days! Learn & Practice with 1000+ FREE Notes, Videos & Tests.
10M+ students study on EduRev