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Lubov Fominskaja [6]
3 years ago
8

How do you know if a reaction is exothermic

Chemistry
2 answers:
melisa1 [442]3 years ago
7 0
When there is heat released
UNO [17]3 years ago
6 0
When heat is released 
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An original sample of K-40 has a mass of 25.00 grams. After 3.9 m 109 years, 3.125 grams of the original sample remains unchange
Svetllana [295]

An original sample of K-40 has a mass of 25.00 grams. After 3.9 m 109 years, 3.125 grams of the original sample remains unchanged. What is the half-life of K-40?

First step is to determine the remaining decimal amount.

3.125 grams /25.00 grams = 0.125

Second step is to determine the number of half lives.

(1/2)^n = 0.125

N log (1/2) = log 0.125

N = 3 years

7 0
4 years ago
What is meant by "elastic collisions"?
Leokris [45]

Elastic collisions meant that there will be no change in the total momentum of the system and surrounding after collision.

<u>Explanation:</u>

Collision is the process where two or more bodies hit each other. So when they hit each other, transfer of energy will be occurring between them. In other words, the momentum can be changed after the collision. There are two kinds of collision.

  • elastic collision
  • inelastic collision

The elastic collision are those which will not undergo any change in the total momentum after collision. This means that the sum of momentum of the objects before collision will be equal to the sum of momentum of the objects after collision. Thus, there will be no change in the total momentum of the object after collision in case of elastic collision.

5 0
3 years ago
What historical event of commercial interest triggered investigation in the science of steam?
Cerrena [4.2K]

Answer: Photosynthesis

Explanation:

5 0
3 years ago
The volume of a fixed mass of a liquid sample increases as the temperature rises from 20 to 40˚c. does the density increase, dec
Mandarinka [93]
Density is the ratio of the substance's mass to volume. To know the effects of temperature on the density of the liquid, we must look at the mass and volume dependence. Mass is always constant, so it is not affected by temperature. For volume, generally, the molecules of the liquid occupy a greater space when heated because of the rapid collisions of the liquid molecules. Thus, as temperature increases, the volume of liquid also increases, although slightly only. That means that density would decrease.
3 0
3 years ago
Which of the following is not an intensive physical property of matter?
Step2247 [10]

Answer:

Concentration

Explanation:

Amount of substance concentration often called simply concentration, is a quantitative measure of the number of atom s per unit volume in a sample of a matter.

5 0
3 years ago
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