ANSWER IS A As you move from left to right across Period 3, which statement is true of the number of

Physics

2 answers:

frosja888 [35]2 years ago

8 0

Answer:

READ YOUR QUESTION CAREFULLY:

If it says left to right, the answer is A. The number of valence electrons increases by 1.

If it says right to left, the answer is B. The number of valence electrons decreases by 1.

Good luck :)

Sedbober [7]2 years ago

7 0

Answer:

A. The number of valence electrons increases by 1.

Explanation:

As you move across any period on the periodic table, the number of valence electrons increases by a value of 1.

The periodic table of elements contains an arrangement of element by their atomic numbers.
From left to right, number of valence electrons increases.
Down a group, the valence electrons are the same.
Across a period, the number of valence electrons increases.

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Water vapor enters a turbine operating at steady state at 500°C, 40 bar, with a velocity of 200 m/s, and expands adiabatically t

faltersainse [42]

Answer:

W = 5701 KW

Explanation:

From the question let inlet be labelled as point 1 and exit as point 2, for the fluid steam, we can get the following;

Inlet (1): P1 = 40 bar ; T1 = 500°C and V1 = 200 m/s

Exit(2) : At saturated vapour; P2 = 0.8 bar and V2 = 150 m/s

Volumetric flow rate = 15 m^(3)/s

Now, to solve this question, we assume constant average values, steeady flow and adiabatic flow.

Specific volume for steam at P2 = 0.8 bar in the saturated vapour state can be gotten from saturated steam tables(find a sample of the table attached to this answer).

So from the table,

v2 = 2.087 m^(3)/kg

Now, mass flow rate (m) = (AV) /v

Where AV is the volumetric flow rate.

Thus, the mass flow rate at exit could be calculated as;

m = 15/(2.087) = 7.17 kg/s

We also know energy equation could be defined as;

Q-W = m[(h1 - h2) + {(V2(^2) - (V1(^2)} /2)} + g(Z2 - Z1)]

Since the flow is adiabatic, potential energy can be taken to be zero. Therefore, we get;

-W = m[(h2 - h1) + {(V2(^2) - (V1(^2)} /2)}

From, table 2, i attached , at P1 = 40 bar and T1 = 500°C; specific enthalpy was calculated to be h1 = 3445.3 KJ/Kg

Likewise, at P2 = 0.8 bar; from the table, we get specific enthalpy as;