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alex41 [277]
3 years ago
6

How many neutrons does element X have if its atomic number is 39 and its mass number is 79?

Physics
1 answer:
bazaltina [42]3 years ago
6 0

Number of neutrons: atomic mass - atomic number

Element X's atomic mass is 79 and its atomic number is 39. Subtract 39 from 79 to find how many neutrons Element X has.

79 - 39 = 40

Element X has 40 neutrons.

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The increase in height as a tsunami approaches shore is due to
ryzh [129]

Answer:

C. The decrease in speed as the wave approaches shore.

Explanation:

The waves break when approaching the shore because the depth decreases. Thus, the wave travels more slowly and increases its height. There comes a time when the part of the wave on the surface travels faster than the one that travels under water, the ridge destabilizes and falls against the ground.

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In a given system of units the ratio of the unit of volume to that of area gives the unit of​
ch4aika [34]

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length

Explanation:

SI unit of volume = m^3

SI unit of area = m^2

volume unit / Area unit = m^3 / m^2

i.e, unit of length

8 0
3 years ago
5. During an anti-bullying club meeting after school, a student mentions that a new student has joined your class at school. The
Oksana_A [137]

Answer:

a. Constant gossiping, and talking negative about a student could cause them to feel very very ill about their beliefs, their familly, school, clothes, etc. this  scenario will make the student feel alienated.

b. The club should advise the students that they should not participate in these talks, allow them into their groups, and should try to talk people out of those conversations.

c. The advice will keep several kids pull away from talking negatively about the kid, help stop the ill intended gossip, and hopefully make them feel better.

5 0
3 years ago
How fast should a moving clock travel if it is to be observed by a stationary observer as running at one-half its normal rate?A)
Elan Coil [88]

Answer:

Option (D) is correct.

Explanation:

Let the speed is v.

\Delta t = \gamma \Delta t'\\\\\Delta t = \frac{1}{\sqrt{1-\frac{v^2}{c^2}}}\times \frac{\Delta t}{2}\\\\\sqrt{1-\frac{v^2}{c^2}} =\frac{1}{2}\\\\1-\frac{v^2}{c^2}=\frac{1}{4}\\\\\frac{3}{4}c^2 = v^2\\\\v = 0.87 c

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4 0
3 years ago
A real power supply can be modeled as an ideal EMF of 60 Volts in series with an internal resistance. The voltage across the ter
lara31 [8.8K]

Answer:

5 ohms

Explanation:

Given:

EMF of the ideal battery (E) = 60 V

Voltage across the terminals of the battery (V) = 40 V

Current across the terminals (I) = 4 A

Let the internal resistance be 'r'.

Now, we know that, the voltage drop in the battery is given as:

V_d=Ir

Therefore, the voltage across the terminals of the battery is given as:

V= E-V_d\\\\V=E-Ir

Now, rewriting in terms of 'r', we get:

Ir=E-V\\\\r=\frac{E-V}{I}

Plug in the given values and solve for 'r'. This gives,

r=\frac{60-40}{4}\\\\r=\frac{20}{4}\\\\r=5\ ohms

Therefore, the internal resistance of the battery is 5 ohms.

5 0
4 years ago
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