NCERT Exercise - Q1
Textbook Exercise Problem
State similarities and differences between the laboratory thermometer and the clinical thermometer.
Step-by-Step Verified Solution:
- Step 1: Similarities: Both contain mercury/alcohol in a sealed glass bulb and operate on thermal expansion of liquids.
- Step 2: Differences: (i) Range: Clinical measures 35°C to 42°C; Laboratory measures -10°C to 110°C. (ii) Kink: Clinical has a constriction/kink preventing mercury from falling back so temperature can be read outside the mouth; Laboratory has no kink.
Final Answer: Similarities: liquid expansion principle; Differences: range (35-42°C vs -10-110°C) and presence of kink.
Key Concept / Exam Strategy: The kink ensures clinical thermometers preserve the patient body reading until manually shaken down.
Generated Exercise #1
Foundation
Question: Convert normal human body temperature (37°C) into Fahrenheit.
Core Concept Tested: Temperature scale conversion equation
Mentor Hint: F = (9/5)C + 32.
Step-by-Step Solution:
- Step 1: F = (9/5) × 37 + 32.
- Step 2: (9 × 37) / 5 = 333 / 5 = 66.6.
- Step 3: F = 66.6 + 32 = 98.6°F.
Verified Answer: 98.6°F
Generated Exercise #2
Intermediate
Question: Why are the bottoms of cooking utensils often blackened or made of copper, while the handles are made of wood or plastic?
Core Concept Tested: Thermal conductors vs insulators
Mentor Hint: Bottom needs fast heat transfer; handle needs thermal protection for hands.
Step-by-Step Solution:
- Step 1: Copper and metals are excellent conductors of heat, ensuring rapid and uniform cooking.
- Step 2: Blackened surfaces maximize absorption of radiation heat.
- Step 3: Wood and plastic/bakelite are poor conductors (insulators), preventing heat from burning user hands.
Verified Answer: Metal bottoms conduct heat rapidly; wooden/plastic handles insulate hands from burns.
Generated Exercise #3
Intermediate
Question: Explain the mechanism of sea breeze during daytime in coastal regions.
Core Concept Tested: Convection currents caused by differential heating
Mentor Hint: Land heats faster than water during daytime.
Step-by-Step Solution:
- Step 1: During daytime, land warms up much faster than sea water due to lower specific heat capacity.
- Step 2: Hot air over land rises, creating a localized low-pressure zone.
- Step 3: Cool, denser air from the sea rushes toward land to replace it. This cool breeze is the Sea Breeze.
Verified Answer: Rapid heating of land causes air to rise; cool air from sea blows toward land creating sea breeze.
Generated Exercise #4
JEE-NEET Foundation
Question: At what temperature do the Celsius and Fahrenheit scales indicate the exact same numerical value?
Core Concept Tested: Algebraic intersection of linear thermometric equations
Mentor Hint: Set C = F = x in C/5 = (F - 32)/9.
Step-by-Step Solution:
- Step 1: Set x/5 = (x - 32)/9.
- Step 2: Cross multiply: 9x = 5(x - 32) = 5x - 160.
- Step 3: 4x = -160 => x = -40.
Verified Answer: -40° (-40°C = -40°F)
Generated Exercise #5
Advanced HOTS
Question: One liter of water at 30°C is mixed with one liter of water at 50°C. What will be the final equilibrium temperature of the mixture? Justify.
Core Concept Tested: Calorimetry principle of heat exchange between equal masses of identical liquids
Mentor Hint: Equal volumes of water have equal mass and equal specific heat.
Step-by-Step Solution:
- Step 1: Heat lost by hot water = Heat gained by cold water.
- Step 2: m × s × (50 - T) = m × s × (T - 30).
- Step 3: 50 - T = T - 30 => 2T = 80 => T = 40°C.
Verified Answer: 40°C (Exactly midway between 30°C and 50°C)