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Alborosie
3 years ago
10

How has telephones change over time

Chemistry
1 answer:
blondinia [14]3 years ago
3 0
Telephones began as large, clunky devices capable of transmitting and receiving voice messages over short distances, then evolved to lighter, transportable cellular devices capable of enabling communications over large distances. In the United States, Alexander Graham Bell receives credit for producing the first telephone in 1876. Bell established a basic system of communications allowing people to talk with each other remotely over short distances through receivers. <span>As with other technologies, phone technologies improved dramatically and rapidly following Bell's introduction of the telephone to American life. In addition to improvements in the device itself, transmissions methods improved as well. By 1900, telephone companies established communication lines through many American cities, allowing people to connect over larger distances. These lines contained special coils to reduce static and expedite transmissions. Telephone calls remained limited to local regions within the borders of the United States through 1915. Then, Alexander Graham Bell completed the first transcontinental call with Thomas Watson. Rotary phones emerged just before 1920, and a numbering plan arrived in the late 1940s to allow fast and direct connections between callers. In 1956, telephone cables permitted transcontinental calls for the first time. In the 1960s and 1970s, phone use extended to emergency service and the military. Portable phones arrived in the early 1970s; by 2000, thousands of Americans carried lightweight, compact phones wherever they went. AND THEY HAVE IPHONES NOW XDD

</span>
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Part A
astraxan [27]

Answer

mass of 1 mole = 18g

mass of 1 mL = 1g

the unit used is gram

Explanation:

There are two ways to find mass of water:

1st way:

If we find Mass of water for one mole of water:

For this purpose we use mole formula as below

                          no. of moles = mass in grams / molar mass

if we find mass for one mole of water:

then

no. of moles of water = 1 mol

molar mass of water = H₂O = (1x2 +1x16) = 18 g/mol

mass of water = ?

Put the value in the mole formula

          no. of moles = mass in grams / molar mass . . . . . . . . . . . . (1)

by rearranging the formula (1)

            mass in grams = no. of moles x molar mass

            mass in grams = 1 mole x 18 g/mol

            mass in grams =  18 g

So for one mole of water the mass of water is 18 g and the unit for it is gram.

2nd way:

We can find mass of water by another way too

if we find the mass 1 mL of water

then the formula will be used is

                              D = m/v

where D is density

m is the mass

and v is the volume

So

density of water for 1 mL (D) = 1 g/ml

volume of water = 1 mL

mass of water = ?

By Rearranging density formula for mass

                                m = D/v ......................... (2)

put the values in equation 2

                                m= 1gmL⁻¹ / 1 mL

                                 m= 1g

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Explanation:

6 0
3 years ago
A mouse is placed in a sealed chamber with air at 769.0 torr. This chamber is equipped with enough solid KOH to absorb any CO2 a
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<u>Explanation:</u>

We are given:

Initial pressure of air = 769.0 torr

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Pressure of oxygen = Pressure decreased = Initial pressure - Final pressure = (769.0 - 717.1) torr = 51.9 torr

To calculate the amount of oxygen gas consumed, we use the equation given by ideal gas which follows:

PV=nRT

where,

P = pressure of the gas = 51.9 torr

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Putting values in above equation, we get:

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Putting values in above equation, we get:

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Answer:

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Explanation:

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