Shawna is trying to figure out the best weight to increase her muscular strength. She has chosen a weight and can lift it two ti
mes. What should she do to get the BEST workout? A. decrease the amount of weight until she can do ten reps B. increase the amount of weight until she can do three reps C. decrease the amount of weight until she can do five reps D. increase the amount of weight until she can do one rep Please select the best answer from the choices provided. A B C D
2 answers:
You might be interested in
Explanation:
The given data is as follows.
Specific heat of water =
Heat of fusion of water = 334 J/g
Mass of water = 200 g
On bringing water at , heat released will be as follows.
=
= -12540 J
or, = -12.540 kJ (as 1 kJ = 1000 J)
Now, calculate the heat releasedwhen water freezes at as follows.
=
= -66800 J
or, = -66.80 kJ
Therefore, total heat released in freezing water will be as follows.
= (-12.540 - 66.80) kJ
= -79.34 kJ
Hence,
amount of heat released in freezing water = heat used to vaporize
Now, heat of vaporization of = 289 J/g
Total heat released in freezing water = -79.34 kJ
Heat consumed to vaporize = 79.34 kJ = -79340 J
Therefore, calculate the mass of vaporized as follows.
Mass of vaporized =
=
= 274.53 g
Thus, we can conclude that 274.53 g mass of this substance must evaporate to freeze 200 g of water initially at .
Answer:
Explanation:
A physical change occurs when only the physical properties change. They are generally reversible and no new substances are formed.
However, in a chemical change, the chemical structures and properties change, plus new substances are formed.
Let's analyze each answer choice.
1. Change in state of matter
The state of matter is a physical property, so this is a physical change.
2. Precipitate was formed
A precipitate is a solid formed in a liquid solution. This is a new substance and a chemical change.
3. Unexpected change in odor.
A change in odor is a sign of chemical change.
4. Formation of bubbles
Bubbles signify the formation of gas or a new substance.
So, the best answer choice is <u>A. change in state of matter</u>