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egoroff_w [7]
3 years ago
6

What is first and second element of the periodic table?

Chemistry
2 answers:
stira [4]3 years ago
7 0
The elements on the periodic table are listed in increasing atomic number. 

Hydrogen is the first element, and has an A.N. of 1. Also, its very interesting how it doesn't need 8 valence electrons to be stable. 

The second element is Helium, which has an A.N (atomic number) of two. 
WINSTONCH [101]3 years ago
6 0

Hydrogen= First element,H

Helium=Second Element,He


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nadezda [96]

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Flashlight

Explanation:

A flashlight gives out heat

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3 years ago
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How many moles of oxygen are required to react completely with 5 mol C8H18?
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Answer:

62.5 moles of O₂.

Explanation:

We'll begin by writing the balanced equation for the reaction. This is illustrated below:

2C₈H₁₈ + 25O₂ —> 16CO₂ + 18H₂O

From the balanced equation above,

2 moles of C₈H₁₈ reacted with 25 moles of O₂.

Finally, we shall determine the number of mole of O₂ needed to react with 5 moles of C₈H₁₈. This can be obtained as shown below:

From the balanced equation above,

2 moles of C₈H₁₈ reacted with 25 moles of O₂.

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6 0
3 years ago
What is a ‘control’ in an experiment?
tensa zangetsu [6.8K]

Answer:

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3 0
3 years ago
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What is the frequency of a photon having an energy of 4.91 × 10–17 ? (c = 3.00 × 108 m/s, h = 6.63 × 10–34 J · s)​
AlexFokin [52]

Answer:

The frequency of the photon is 7.41*10¹⁶ Hz

Explanation:

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where E is the energy, h the Planck constant (whose value is 6.63*10⁻³⁴ J.s) and v the frequency (Hz or s⁻¹).

So the frequency will be:

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Being E= 4.91*10⁻¹⁷ J and replacing:

v=\frac{4.91*10^{-17} J}{6.63*10^{-34} J.s}

You can get:

v= 7.41*10¹⁶ \frac{1}{s}= 7.41*10¹⁶ Hz

<u><em>The frequency of the photon is 7.41*10¹⁶ Hz</em></u>

<u><em></em></u>

4 0
3 years ago
Describe how to separate a mixture of sugar and water.
Nonamiya [84]
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4 years ago
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