Ask question

Ask question

All categories

3 years ago

5

Draw the model of an atom with an atomic number of 7 and a mass number of 15. How many valence electrons are in this atom.

1 answer:

o-na [289]3 years ago

7 0

Answer:

There are 5 valence electrons

Explanation:

Valence electrons are electrons found in the outermost shell of an atom.

You might be interested in

A 59 kg man has a total mechanical energy of 150,023. J. If he is swinging downward and is currently 2.6 m above the ground, wha

Alborosie

Answer:

$v = 70.95 \ m/s.$

Explanation:

Given data:

Mass of the man, $m = 59 \ kg$

Total mechanical energy, $E_{i} = 150,023 \ \rm J$

Height, $h = 2.6 \ m$

Suppose there is no external force acting on the man. In this situation, the total mechanical energy (kinetic + potential) will remain steady.

Let the speed of the man at 2.6 m be <em>v</em>.

Thus,

$E_{i} = E_{f}$

$E_{i} = \frac{1}{2}mv^{2} + mgh$

$150023 = 0.5 \times 59 \times v^{2} + 59 \times 9.80 \times 2.6$

$\Rightarrow \ v = 70.95 \ m/s.$

6 0

3 years ago

How do you spell hard water in three letters.

Kay [80]

Ice, which is the solid state of water, the liquid

5 0

4 years ago

Read 2 more answers

Why did Thomson observe two glowing dots when he put neon gas into a<br> cathode-ray tube?

Artist 52 [7]

Answer:

Electrons accelerated to high velocities travel in straight lines through an empty cathode ray tube and strike the glass wall of the tube, causing excited atoms to fluoresce or glow.

7 0

3 years ago

A scientist would use a balance to measure

GrogVix [38]

Answer is B

Hope it Helps!

7 0

4 years ago

Read 2 more answers

4. A 70.0 kg boy and a 45.0 kg girl use an elastic rope while engaged in a tug-of-war on an icy,

marta [7]

Answer:

$a_1 = 1.446m/s^2$

Explanation:

Given

$m_1 = 70.0kg$ -- Mass of the boy

$m_2 = 45.0kg$ -- Mass of the girl

$a_2 = 2.25m/s^2$ -- Acceleration of the girl towards the boy

Required

Determine the acceleration of the boy towards the girl ( $a_1$ )

From the question, we understand that the surface is frictionless. This implies that the system is internal and the relationship between the given and required parameters is:

$m_1 * a_1 = m_2 * a_2$

Substitute values for $m_1, m_2$ and $a_2$

$70.0 * a_1 = 45.0 * 2.25$

Make $a_1$ the subject

$\frac{70.0 * a_1}{70.0} = \frac{45.0 * 2.25}{70.0}$

$a_1 = \frac{45.0 * 2.25}{70.0}$

$a_1 = \frac{101.25}{70.0}$

$a_1 = 1.446m/s^2$

<em>Hence, the acceleration of the boy towards the girl is 1.446m/s^2</em>

7 0

3 years ago