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3 years ago

What are two ways to tell if a chemical reaction is taking place?

2 answers:

6 0

A chemical reaction is observed by physical effects that cannot be undone, for Ex. If an object give off heat or light, thats a chemical reaction. If theirs a change in an objects color it can be a chemical reaction, like rust. Metal turning silver to brown. <span />

Kruka [31]3 years ago

4 0

1) temperature change
2)odor or smell change
Hope this helps

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#1: How are the elements arranged in the modern periodic table?

Alekssandra [29.7K]

1- The correct answer is C :

the elements arranged in the modern periodic table by increasing atomic number.

The explanation:

-The elements in the periodic table are arranged to increase the atomic number. All of these elements display several other trends and we can use the periodic law and table formation to predict their chemical, physical, and atomic properties.

2- The correct answer is C:

strontium, magnesium, calcium, beryllium are the elements which have similar properties.

The explanation:

-strontium, magnesium, calcium, beryllium, these belong to the alkaline earth metal group.

Because the outer electron structure in all of these elements is similar, they all have somewhat similar chemical and physical properties .

3- The correct answer is A :

Potassium

The explanation:

-The elements potassium and sodium have similar chemical properties because they have the same number of valence electrons and form +1 ions.

4- The correct answer is D

The explanation:

Mendeleev didn't include helium, neon, and argon in his periodic table because these elements had not yet been discovered.

5- The correct answer is B:

The periodic law describes trends seen across periods within the periodic table.

The explanation:

When the chemical elements are arranged, there is a pattern called the “periodic law” in their properties, in which elements in the same column (group) have similar properties

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3 years ago

Read 2 more answers

When you receive a loan, the money the lender gives you is called the ____________. A. Interest B. Line of credit C. Principal D

Reika [66]

C. Principal !!!!!!!!!

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3 years ago

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Compare What do infrared technologies, fiber optic

LuckyWell [14K]

Answer:

ptic fiber communication and satellite communication are the leading technologies which are revolutionizing the world of telecommunications. Both technologies have their advantages and limitations which make them suitable for certain type of applications. This article will provide an overview of optic fiber and satellite communication technologies and present a comparison of the features and related issues.

Optic Fiber Communication

Optic Fiber communication transmits information by sending pulses of light (using laser) through an optic fiber. The low signal loss in optic fibers and high data rate of transmission systems, allow signals with high data rates (exceeding several Gbps) to travel over long distances (more than 100 km) without a need of repeater or amplifier. Moreover, using wavelength division multiplexing (WDM) allows a single fiber to carry multiple signals (upto 10 different signals) of multi-Gbps transmissions. Optic Fiber communication offers extremely high bandwidth, immunity to electromagnetic interference, non-existent delays and immunity from interception by external means. In the 1980s and 1990s, the continents were linked together using undersea optic fiber bringing about a paradigm shift in the global telecommunications.

These advancements in optic fiber communication has resulted in decrease of satellite communications for several types of communications. For instance, transmission between fixed locations or point-to-point communications, where large bandwidths are required (such as transoceanic telephone systems) are made through optic fiber instead of using satellite communication. Optic Fiber communication is also used to transmit telephone signals, Internet communication, LAN (Gigabit LAN) and cable television signals.

Satellite Communication

Satellite communications use artificial satellites as relays between a transmitter and a receiver at different locations on Earth. Satellite systems allow users to bypass typical carrier offices and to broadcast information to multiple locations. Communications satellites are used for radio, TV, telephone, Internet, military and other applications. There are more than 2,000 satellites around Earth’s orbit, being used for communication by both government and private organizations.

Communication Satellites are LOS (line-of-sight) microwave systems with a repeater. These satellites rotate around the earth with the speed of earth and are known as geostationary satellites. The limitations of antenna size also limits focusing capability making the coverage for a single satellite transmitter very large. This makes satellite communication ideal for TV and radio services as the signal has to flow from a single point to many points in a single direction. The large distance of satellites from the earth (about 22,300 miles) results in delays which adversely effects two-way communication like mobile conversations. Low earth orbit satellites can be used for two-way mobile communication because less power is required to reach those satellites.

Explanation:

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2 years ago

Why are the red blood cells crescent-shaped

Lesechka [4]

Answer:

The ref blood cells are shaped like sickles or crescent moons, sticky cells can get stuck in small blood vessels which can slow or block blood flow and oxygen to parts of the body

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2 years ago

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If you start with 10ml of 0.75 m cu(no3)2 how much cu (s) in grams should be recovered in step #7

LenaWriter [7]

<span>0.48 grams. Not a well worded question since it's assuming I know the reactions. But I'll assume that since there's just 1 atom of copper per molecule of Cu(NO3)2, that the reaction will result in 1 atom of copper per molecule of Cu(NO3)2 used. With that in mind, we will have 0.010 l * 0.75 mol/l = 0.0075 moles of copper produced. To convert the amount in moles, multiply by the atomic weight of copper, which is 63.546 g/mol. So 0.0075 mol * 63.546 g/mol = 0.476595 g. Round the results to 2 significant figures, giving 0.48 grams.</span>

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3 years ago