Verified Solution • 2025–26 Session moderate

Q10.2: NCERT Physics - Part 2 THERMAL PROPERTIES OF MATTER 10.2 Solution: Two absolute scales A and B have triple points of water defined …

⚠️ Common Exam Traps & Conceptual Pitfalls

Students often incorrectly assume the temperature ratio equals the triple point ratio ($T_A/T_B = 350/200$) or invert the final fraction. Remember that the size of one degree is inversely proportional to the triple point value, so the temperature values are directly proportional to the triple point values ($T_A/T_B = 200/350$).

Two absolute scales A and B have triple points of water defined to be 200 A and 350 B. What is the relation between

T_A

and

T_B

?

Step-by-Step Verified Solution

**Answer:**

T_A : T_B = 4 : 7

**Step-by-Step Explanation:** The triple point of water on the Kelvin scale is 273.15 K. On scale A: 200 A = 273.15 K, so

1 \text{ A} = \frac{273.15}{200}

K. On scale B: 350 B = 273.15 K, so

1 \text{ B} = \frac{273.15}{350}

K. If

T_A

and

T_B

are the same physical temperature on the two scales:

\frac{273.15}{200} T_A = \frac{273.15}{350} T_B

\frac{T_A}{200} = \frac{T_B}{350}

\frac{T_A}{T_B} = \frac{200}{350} = \frac{4}{7}

Hence,

T_A : T_B = 4 : 7

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All Questions in this Chapter

Q10.1 Q10.2 Q10.3 Q10.4 Q10.5 Q10.6 Q10.7 Q10.8 Q10.9 Q10.10 Q10.11 Q10.12 Q10.13 Q10.14 Q10.15 Q10.16 Q10.17 Q10.18 Q10.19 Q10.20

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