Chemistry Praxis Exam Prep
Questions And Answers 2023
The specific heat of liquid water is 1 cal/kg°C. The specific heat of ice is half of that, at
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0.5 cal/kg°C. Compared with that for 2 kg of liquid water, how much heat is needed to
change the temperature of 2 kg of ice by 10°?
1. Four times as much heat is needed to change the temperature of the ice.
2. Twice as much heat is needed to change the temperature of the ice.
3. Half as much heat is needed to change the temperature of the ice.
4. One fourth as much heat is needed to change the temperature of the ice. - ANS-3.
Half as much heat is needed to change the temperature of the ice.
Which of the following correctly explains the difference between heat and thermal
energy in science?
1. An object has thermal energy, but heat is transferred between objects.
2. An object has heat, but thermal energy is transferred between objects.
3. There is no difference. Heat and thermal energy are the same thing.
4. Heat is a measure of how hot an object is, whereas thermal energy is a measure of
how fast the object's molecules move. - ANS-1. An object has thermal energy, but heat
is transferred between objects.
The specific heat of oak is 0.58 cal/g°C. How much heat is required to change the
temperature of 10 grams of oak by 10°C?
1. 5.8 cal
2. 580 cal
3. 0.58 cal
4. 58 cal - ANS-4. 58 cal
Which of the laws of thermodynamics prohibits any process from being 100% efficient?
1. the zeroth law
2. the first law
3. the second law
4. The first and second laws when taken together prohibit 100% efficiency. - ANS-3. the
second law; often called the law of entropy; prohibits 100% efficiency in any process
Determine the change in internal energy of a pot of eggs put on the stove and brought
to a boil if 200 kJ of heat is added to the water, 80 kJ of heat escapes from the pot, and
the escaping steam does 25 kJ of work vibrating and lifting the lid of the pot.
1. 95 kJ
2. 175 kJ
3. 145 kJ
4. 305 kJ - ANS-1. 95kJ (delta U = Q - W)
Which of the following will give off energy if used as fuel in a fission reaction?... [Show Less]