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3 years ago

The spectra of most stars are dark-line spectra because ________.

1 answer:

5 0

Because dark line spectra result from passing white light through ionized gasses and plasmas, which is what the atmosphere of stars are made of. These frequencies are scattered by the star's atmosphere as it leaves the surface (photosphere) of the star, and don't make it to earth.

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A neutral atom possesses an atomic number of 13 and an atomic mass of 27. Three electrons are lost. From what region of the atom

slega [8]

The atomic number of the atom is 13. This means that its electronic configuration is (2 8 3) or in other words:
1s2, 2s2, 2p6, 3s2, 3p1

If three electrons are lost, then these electrons are removed from the outermost level.
In our case, electrons are removed from the third energy level (one electron is removed from the 3p orbital and two electrons are removed from the 3s orbital).

8 0

3 years ago

In a certain process, the energy of the system decreases by 250 kJkJ. The process involves 480 kJkJ of work done on the system.

BigorU [14]

Answer:

-730KJ

Explanation:

According to the first law of thermodynamics;

Let the total energy of the system be ∆E

Let heat be q and let work the w

Since the energy decreases ∆E is negative

Since work is done on the system w= positive

So;

- 250 = 480 + q

q = -250 - 480

q=-730KJ

5 0

3 years ago

A microwave oven operates at 2.50 GHzGHz . What is the wavelength of the radiation produced by this appliance? Express the wavel

sattari [20]

Answer:

The wavelength is $\lambda = 1.2 * 10^8 nm$

Explanation:

From the question we are told that

The frequency of operation of the microwave is $f = 2.50 GHz = 2.50 *10^{9} \ Hz$

Generally the wavelength is mathematically represented as

$\lambda = \frac{c}{f}$

Here c is the speed of light with value $c = 3.0 *10^{8} \ m/s$

$\lambda = \frac{3.0 *10^{8}}{ 2.50 *10^{9}}$

=> $\lambda = 0.12 \ m$

converting to nanometer

$\lambda = 1.2 * 10^8 nm$

6 0

3 years ago

the pull of gravity on mars is 3.7m/s^2. if a astronaut on mars lifts a 10 kg rock 1 m off the ground, just to see whats under i

Elanso [62]

Gravitational potential energy can be calculated using the formula:

$PE_{grav} =mgh$

Where:
PEgrav = Gravitational potential energy
m= mass
g = acceleration due to gravity
h = height

On Earth acceleration due to gravity is a constant 9.8 but since the scenario is on Mars, the pull of gravity is different. In this case, it is 3.7, so we will use that for g.

So put in what you know and solve for what you don't know.
m = 10kg
g = 3.7m/s^2
h = 1m

So we put that in and solve it.
$PE_{grav} =mgh$
$PE_{grav} =(10kg)(3.7m/s^{2})(1m)$
$PE_{grav} =37J$

7 0

4 years ago

Which part of the telescope gathers light from a faraway object and reflects it to another mirror?

melamori03 [73]

Answer:

2)primary mirror

Explanation:

A reflecting telescope contains mirrors and a refracting telescope contains lenses. There are two mirrors in basic reflecting telescope. The primary mirror gathers the light from the bodies at distance and reflects it towards the secondary mirror. The secondary mirror is placed at such an angle that it then reflects the light towards the eye piece and we can observe the faraway body.

5 0

4 years ago