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12345 [234]
3 years ago
8

When Dimitri Mendelev first developed the periodic table, one of the most important features that he introduced was starting a n

ew row at a certain point. What factor was most important to Mendelev in knowing when to end a row (period) and start a new one? A) The reactivity of the elements changed drastically. B) The state of the elements went from solid to liquid. C) The boiling point of the elements decreased dramatically. D) The size of the elements jumped from very large to very small.
Chemistry
2 answers:
sashaice [31]3 years ago
6 0

Answer:

A

Explanation:

Phantasy [73]3 years ago
3 0

At the end of a period we get an inert gas which is  very unreactive compared with the previous element ( a halogen).

The answer is A.

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Answer:

domain bacteria

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Salmonella and E. coli are same in the sense that they are both bacteria,

7 0
3 years ago
PLEASE ANSWER FAST!!!!!!!!!!!!!!!
Savatey [412]

Answer:

The answer is A. a wave of vibrating electric and magnetic energy.

6 0
3 years ago
Which statement is true of a chemical change?
Andru [333]
The appropriate answer is a. it involves a change in the molecular structure of the substance. A change in phase or state is referred to as a physical change. For example...liquid water freezing is a physical change because the state changes but solid water is still H20. Separating water into its constituent atoms, hydrogen and oxygen is a chemical change because the molecular structure of water is now non existent.
5 0
3 years ago
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A compound is formed when 171.2 g of carbon reacts with 28.8 g of hydrogen. What is the mass percent of hydrogen in the compound
IgorLugansk [536]
Following the law of conservation of mass, the mass percent of hydrogen in the resulting compound is 14.4%(wt/wt). This is assuming that all of the carbon reacts with all of the hydrogen. The solution is as follows:

mass % = mass hydrogen*100/total mass = 28.8*100/(28.8+171.2) = 14.4%
4 0
3 years ago
.. can someone answer these quickly before I go to bed
elixir [45]

Ans

1. d.x-Rays

2. d.modern medical x-rays use stronger radiation than earlier types.

3. b.Radio waves have high frequency

4.a.Gamma radiation

5.b.Infrared radiation

6.a.Radio waves

<u>Explanation:</u>

  • A mammogram is an X-ray of the breast. Mammograms are commonly used to screen for breast cancer.
  • Radio-tracking technology assists in determining exactly where an animal is located at any instant in time and frequently what that animal is performing! Utilizing the data collected from tracking devices, scientists can conclude the day-to-day activities of an animal, the size of an animal's place range, what other animals share an animal's range and the types of habitats an animal practices.
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8 0
3 years ago
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