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mr Goodwill [35]

3 years ago

10

Which best explains why the noble gases are chemically unreactive? They have no valence electrons. They have the same number of

protons and electrons. They have more neutrons than protons. They have very stable outer electron shells.

2 answers:

miskamm [114]3 years ago

8 0

They have very stable outer electron shells

Alex777 [14]3 years ago

4 0

They have very stable outer electron shells

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5. A stream of air at 12 bar and 900 K is mixed with another stream of air at 2 bar and 400 K with 2 times the mass flowrate. If

Softa [21]

Answer:

The anserrs to the question are

(a) The temperature would be 566.67 K and

(b) The pressure of the resulting air stream is 14 bar

Explanation:

Here the two streams of gases meet ad form a single stream

The steady-flow energy equation can be implemented at the mixing point of the to streams as follows

mₐhₐ₁ + mₙ hₙ₁ + Q° + W° = mₐhₐ₂ + mₙhₙ₂

Where the flow is adiabatic, we have

Q = 0 and W = 0 hence

mₐhₐ₁ + mₙ hₙ₁ = mₐhₐ₂ + mₙhₙ₂ where h = cp×T we have

mₐcpₐ×Tₐ + mₙcpₙ×Tₙ = mₐcpₐ×T + mₐcpₙ×T

Therefore the final temperature T is given by

$T = \frac{m_ac_{pa}T_a + m_nc_{pn}T_n}{m_ac_{pa} + m_nc_{pn}}$ for the same kind of gas cpₐ =cpₙ therefore

$T = \frac{m_aT_a + m_nT_n}{m_a + m_n}$ where mₐ and mₙ are mass flow rate

Therefore we have where Tₐ = = 900 K and Tₙ = 400 K and mₙ = 2mₐ gives

$T = \frac{m_a*900 + 2*m_a*400}{m_a + 2*m_a}$ = $T = \frac{900 + 800}{1 + 2}$ = 1700/3 = 566.67 K

From Dalton's law, the total pressure of a mixture of gases is equal to the sum of the partial pressures of the components of the mixture

Therefore the total pressure of the combined stream = pₐ + pₙ = p

= 12 bar + 2 bar = 14 bar

Stream pressure = 14 bar

4 0

3 years ago

If no friction acts on a diver during a dive, then which of the following statements is true? A) The total mechanical energy of

EleoNora [17]

If no frictional work is considered, then the energy of the system (the driver at all positions is conserved.

Let
position 1 = initial height of the diver (h₁), together with the initial velocity (v₁).
position 2 = final height of the diver (h₂) and the final velocity (v₂).

The initial PE = mgh₁ and the initial KE = (1/2)mv₁²
where g = acceleration due to gravity,
m = mass of the diver.
Similarly, the final PE and KE are respectively mgh₂ and (1/2)mv₂².
PE in position 1 is converted into KE due to the loss in height from position 1 to position 2.

Therefore
(KE + PE) ₁ = (KE + PE)₂

Evaluate the given answers.
A) The total mechanical energy of the system increases.
FALSE

B) Potential energy can be converted into kinetic energy but not vice versa.
TRUE

C) (KE + PE)beginning = (KE + PE) end.
TRUE

D) All of the above.
FALSE

4 0

4 years ago

Read 2 more answers

A long solenoid (radius = 3.0 cm, 2500 turns per meter) carries a current given by I = 0.30 sin(200 t) A, where t is measured in

I am Lyosha [343]

Answer:

1.86 × 10 ∧-3 V/m

≅ 1.9 × 10 ∧-3 V/m

Explanation:

Radius of long solenoid (R)= 3 cm

Turns per meter (n) = 2500

current flowing in coil (I) = 0.30 sin (200 t)

Time (t) = 2.5 ms

Distance at which electric field calculated (r) = 4 cm

The main solution is shown in the picture attached below.

Thank you and i hope it helps.

4 0

3 years ago

sashaice [31]

Given that,

Electrical energy of the motor = 2280 J

Kinetic energy = 1606 J

Wasted energy in thermal and sound energy = 550 J

To find,

The efficiency of the motor in percent.

Solution,

Efficiency is defined as the ratio of useful output energy to the total energy.

Total energy = 2280 J

Useful energy = 1606 J

$\eta=\dfrac{1606}{2280}\times 100\\\\=70.43\%$

So, the efficiency of the motor is 70.43%.

5 0

3 years ago

When the north pole of a magnet is moved towards the center of a loop of wire containing a galvanometer, the needle of the galva

andriy [413]

Answer:

Moving the magnet away from the center of the loop with its south pole facing the center of the loop.

Explanation:

Electromagnetic induction is due to a rapidly changing magnetic field, or loop area. The poles of the magnet induce current in the loop but in the opposite direction, depending on the direction of their relative motion. An approaching north pole will induce an anticlockwise current in the loop, while an approaching south pole will do the reverse. To get the galvanometer to flicker in the same direction as of that when the north pole was approaching, we move the magnet away from the center of the loop with its south pole facing the center of the loop.

6 0

3 years ago