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3 years ago

Which of the following lists contains only elements?

Chemistry

1 answer:

Alexxandr [17]3 years ago

5 0

C. air, fire, water, earth. 4 elements

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It takes 495.0 kJ of energy to remove 1 mole of electron from an atom on the surface of sodium metal. How much energy does it ta

Zigmanuir [339]

Answer:

$\lambda=241.9\ nm$

Explanation:

The work function of the sodium= 495.0 kJ/mol

It means that

1 mole of electrons can be removed by applying of 495.0 kJ of energy.

Also,

1 mole = $6.023\times 10^{23}\ electrons$

So,

$6.023\times 10^{23}$ electrons can be removed by applying of 495.0 kJ of energy.

1 electron can be removed by applying of $\frac {495.0}{6.023\times 10^{23}}\ kJ$ of energy.

Energy required = $82.18\times 10^{-23}\ kJ$

Also,

1 kJ = 1000 J

So,

Energy required = $82.18\times 10^{-20}\ J$

Also, $E=\frac {h\times c}{\lambda}$

Where,

h is Plank's constant having value $6.626\times 10^{-34}\ Js$

c is the speed of light having value $3\times 10^8\ m/s$

So,

$79.78\times 10^{-20}=\frac {6.626\times 10^{-34}\times 3\times 10^8}{\lambda}$

$\lambda=\frac{6.626\times 10^{-34}\times 3\times 10^8}{82.18\times 10^{-20}}$

$\lambda=\frac{10^{-26}\times \:19.878}{10^{-20}\times \:82.18}$

$\lambda=\frac{19.878}{10^6\times \:82.18}$

$\lambda=2.4188\times 10^{-7}\ m$

Also,

1 m = 10⁻⁹ nm

So,

$\lambda=241.9\ nm$

6 0

2 years ago

When a spacecraft travels away from Earth, the gravitational force acting on it (2 points)

mrs_skeptik [129]

SInce earths gravitational force is 9.81, and outer space is less than that, the force decreases

3 0

3 years ago

Read 2 more answers

How do you toast a toaster?

Mama L [17]

by putting to much current through it ?

7 0

2 years ago

Each incomplete reaction is a neutralization reaction. Match each equation with the salt formed. 1. H2SO4 + 2NH4OH → ? 2. 2NaOH

sergey [27]

1. H₂SO₄ + 2NH₄OH ⟶ (NH₄)₂SO₄ + 2H₂O

2. 2NaOH + H₂CO₃ ⟶ Na₂CO₃ + 2H₂O

3. HNO₃ + KOH ⟶ KNO₃ + H₂O

<em>Explanation</em>:

Acid + base ⟶ salt + water

Take the H from the acid and the OH from the base to get water.

Then, join what’s left to get the salt. Write the symbol for the metal first.

For example, in equation 3, take the H from HNO₃ and the OH from KOH.

Combining the remaining parts (NO₃ and K) to get the salt, KNO₃.

7 0

3 years ago

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8.7g+15.43g+19g?<br> 853.2L-627.443L?<br> 5.47m+11m+87.300m?

gizmo_the_mogwai [7]

the god ran down the street

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3 years ago