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3 years ago

BRAINLIEST + 20 POINTS FOR BEST ANSWER!!!

Chemistry

2 answers:

liq [111]3 years ago

4 0

Each type of electromagnetic radiation have been matched to their descriptions as follows:

Ultraviolet light A) Given off by very hot objects, such as the sun

Gamma rays B) Given off by radioactive substances

Microwaves C) Used in radar and to heat food

X‒rays D) Used in the medical field to see bone structure

Zina [86]3 years ago

4 0

Answer :

Ultraviolet light - (A) Given off by very hot objects, such as the sun

Gamma rays - (B) Given off by radioactive substances

Microwaves - (C) Used in radar and to heat food

X-rays - (D) Used in the medical field to see bone structure

Explanation :

Electromagnetic waves : It is a wave in which two vectors are vibrating mutually perpendicular to each other and in direction of the wave. The two vectors are electric field and magnetic field.

The gamma-rays, x-rays, ultraviolet-rays, infrared-rays, microwaves and radio-waves are the electromagnetic waves.

Ultraviolet light : It is a form of light that is not visible to the human eye. It is given off by very hot objects such as sun. The U.V light are harmful for living beings.

Gamma rays : It is arising from the radioactive decay of atomic nuclei. It has shortest wavelength waves and imparts high photon energy can pass through most forms of matters because they have no mass.

Microwaves : It is a wave having wavelength range 0.001-0.3 m is shorter than that of normal radio wave but greater than of infrared wave. It is used in the radar and to heat the food.

X-rays : It is a high energy wave and very short wavelength. It has ability to pass through many materials. It is used in the medical field to see the bone structure.

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When the volume and number of particles of a gas are constant which of the following is also constant

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Answer:

The product of the pressure and volume.

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3 years ago

A 27 kg iron block initially at 375 C is quenched in an insulated tank that contains 130kg of water at 26 C. Assume the water th

Bess [88]

Solution :

a). Applying the energy balance,

$\Delta E_{sys}=E_{in}-E_{out}$

$0=\Delta U$

$0=(\Delta U)_{iron} + (\Delta U)_{water}$

$0=[mc(T_f-T_i)_{iron}] + [mc(T_f-T_i)_{water}]$

$0 = 27 \times 0.45 \times (T_f - 375) + 130 \times 4.18 \times (T_f-26)$

$t_f=33.63^\circ C$

b). The entropy change of iron.

$\Delta s_{iron} = mc \ln\left(\frac{T_f}{T_i} \right)$

$= 27 \times 0.45\ \ln\left(\frac{33.63 + 273}{375 + 273} \right)$

= -9.09 kJ-K

Entropy change of water :

$\Delta s_{water} = mc \ \ln\left(\frac{T_f}{T_i} \right)$

$= 130 \times 4.18\ \ln\left(\frac{33.63 + 273}{26 + 273} \right)$

= 10.76 kJ-K

So, the total entropy change during the process is :

$\Delta s_{tot} = \Delta s_{iron} + \Delta s_{water}$

= -9.09 + 10.76

= 1.67 kJ-K

c). Exergy of the combined system at initial state,

$X=(U-U_{0}) - T_0(S-S_0)+P_0(V-V_0)$

$X=mc (T-T_0) - T_0 \ mc \ \ln \left(\frac{T}{T_0} \right)+0$

$X=mc\left((T-T_0)-T_0 \ ln \left(\frac{T}{T_0} \right)\right)$

$X_{iron, i} = 27 \times 0.45\left(((375+273)-(12+273))-(12+273) \ln \frac{375+273}{12+273}\right)$

$X_{iron, i} =63.94 \ kJ$

$X_{water, i} = 130 \times 4.18\left(((26+273)-(12+273))-(12+273) \ln \frac{26+273}{12+273}\right)$

$X_{water, i} =-13.22 \ kJ$

Therefore, energy of the combined system at the initial state is

$X_{initial}=X_{iron,i} +X_{water, i}$

= 63.94 -13.22

= 50.72 kJ

Similarly, Exergy of the combined system at initial state,

$X=(U_f-U_{0}) - T_0(S_f-S_0)+P_0(V_f-V_0)$

$X=mc\left((T_f-T_0)-T_0 \ ln \left(\frac{T_f}{T_0} \right)\right)$

$X_{iron, f} = 27 \times 0.45\left(((33.63+273)-(12+273))-(12+273) \ln \frac{33.63+273}{12+273}\right)$

$X_{iron, f} = 216.39 \ kJ$

$X_{water, f} = 130 \times 4.18\left(((33.63+273)-(12+273))-(12+273) \ln \frac{33.63+273}{12+273}\right)$

$X_{water, f} =-9677.95\ kJ$

Thus, energy or the combined system at the final state is :

$X_{final}=X_{iron,f} +X_{water, f$

= 216.39 - 9677.95

= -9461.56 kJ

d). The wasted work

$X_{in} - X_{out}-X_{destroyed} = \Delta X_{sys}$

$0-X_{destroyed} =$

$X_{destroyed} = X_{initial} - X_{final}$

= 50.72 + 9461.56

= 9512.22 kJ

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