alleryA 40 L mix has 30% acid. Acid in litres:
- 12
- 8
- 10
- 14
Show answer and solution
Correct answer: A. 12
1. 30% of 40 = 12 L.
_Source: 501-GMAT-Questions Section 4 / Manhattan Quant Bank_
ICSE Class 10 Chemical Changes, Reactions & Atmospheric Pollution — practice questions
Explore 50 free Chemical Changes, Reactions & Atmospheric Pollution questions in ICSE Class 10 Chemistry. Open each question or exercise to read its content, reference answers and available explanation.
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A 40 L mix has 30% acid. Acid in litres:Read the answer and worked solution →One kilogram of ice at 0°C melts into water at 0°C. The latent heat of fusion for water is 334 kJ/kg. What is the increase in entropy of the ice during this melting?Read the answer and worked solution →When are two objects in contact said to be in thermal equilibrium?Read the answer and worked solution →The zeroth law of thermodynamics is compared to which mathematical property?Read the answer and worked solution →Why is the zeroth law of thermodynamics given a number lower than the first and second laws?Read the answer and worked solution →How is pressure defined in terms of force and area?Read the answer and worked solution →What is the SI unit of pressure?Read the answer and worked solution →What is the value of the Boltzmann constant k used in the ideal gas law?Read the answer and worked solution →In the first law equation, ΔU = Q minus W, what sign convention applies to Q and W?Read the answer and worked solution →What is internal energy, as defined for a physical system?Read the answer and worked solution →During photosynthesis, plants convert incoming solar radiation into which form of energy?Read the answer and worked solution →How does eating relate to the first law of thermodynamics, as applied to the human body?Read the answer and worked solution →What does entropy measure in a physical system?Read the answer and worked solution →1.00 kg of ice at 0 degrees Celsius (273 K) absorbs 3.34 x 10^5 J of heat while melting into water at 0 degrees Celsius. What is the increase in entropy?Read the answer and worked solution →3.00 kg of ice at 0 degrees Celsius (273 K) melts into water at 0 degrees Celsius. Using Lf(water) = 334 kJ/kg, what is the increase in entropy?Read the answer and worked solution →Can the entropy of one part of the universe, such as a system built by doing work, ever decrease?Read the answer and worked solution →What is a cyclical process, as used to describe heat engines?Read the answer and worked solution →A heat engine is given 120 J of heat and releases 20 J of heat to the environment. How much work does it do?Read the answer and worked solution →A heat engine takes in 6.0 kJ of heat and produces 4.8 kJ of waste heat. What is its efficiency?Read the answer and worked solution →A coal power station operates at 40.0 percent efficiency and takes in 1.20 x 10^12 J by heat. How much work does it do?Read the answer and worked solution →A coal power station transfers 3.0 x 10^12 J by heat from burning coal and releases 1.5 x 10^12 J by heat into the environment. What is its efficiency?Read the answer and worked solution →In the heat pump described, which component raises the temperature and pressure of the working fluid using electrical work?Read the answer and worked solution →What condition would be required for a heat engine to reach 100 percent thermal efficiency?Read the answer and worked solution →The sound sentenceRead the answer and worked solution →A process spontaneous in one direction under given conditions is, in reverse:Read the answer and worked solution →A solution that can dissolve no more solute is:Read the answer and worked solution →A bus goes at 40 km/h and returns by the same road at 60 km/h. Average speed overall?Read the answer and worked solution →A stone is dropped from rest and falls freely for 3 s (g = 10 m/s squared). How far does it fall?Read the answer and worked solution →On a plot of velocity against time, the slope of the line represents which quantity?Read the answer and worked solution →An observer moves towards a stationary bell. What do they hear?Read the answer and worked solution →
Worked practice questions
One kilogram of ice at 0°C melts into water at 0°C. The latent heat of fusion for water is 334 kJ/kg. What is the increase in entropy of the ice during this melting?
- 3.34 x 10^2 J/K
- 3.34 x 10^3 J/K
- 6.11 x 10^2 J/K
- 1.22 x 10^3 J/K
Show answer and solution
Correct answer: D. 1.22 x 10^3 J/K
1. First find the heat needed to melt the ice: Q = m x Lf = (1.00 kg)(334 kJ/kg) = 334 kJ = 3.34 x 10^5 J.
2. Convert the melting temperature to kelvins: T = 0°C + 273 = 273 K.
3. Apply the entropy definition: ΔS = Q/T = (3.34 x 10^5 J)/(273 K).
4. Carrying out the division: 3.34 x 10^5 / 273 = 1.22 x 10^3 J/K.
5. Option A, 3.34 x 10^2 J/K, and option B, 3.34 x 10^3 J/K, both just rescale the heat Q itself rather than dividing it by the temperature.
6. Option C, 6.11 x 10^2 J/K, does not follow from dividing 3.34 x 10^5 J by 273 K, so it does not match the required substitution.
_Source: OpenStax College Physics (CC BY 4.0), Ch 15 "Thermodynamics", section 15.6 Entropy and the Second Law of Thermodynamics: Disorder and the Unavailability of Energy_
When are two objects in contact said to be in thermal equilibrium?
- When they are at the same pressure
- When they are at the same temperature
- When they have equal masses
- When they have equal volumes
Show answer and solution
Correct answer: B. When they are at the same temperature
1. When two objects in contact reach the same temperature, no more net heat transfer occurs between them.
2. This condition, where temperatures are equal and stable, is called thermal equilibrium.
3. Pressure, mass, and volume are separate physical quantities and are not what defines thermal equilibrium.
4. So equal temperature is correct.
_Source: OpenStax Physics (CC BY 4.0), Ch 12 "Thermodynamics", section 12.1 Zeroth Law of Thermodynamics: Thermal Equilibrium_
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