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lukranit [14]
3 years ago
14

When was the last time that humans have left Earths orbit?

Chemistry
2 answers:
Vinvika [58]3 years ago
6 0

Answer:

d

Explanation:

svp [43]3 years ago
4 0

Answer:

b.  1972 ......

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Which element requires the least i.e. potassium or gallium why
-Dominant- [34]

Answer:

Potassium

General Formulas and Concepts:

<u>Chem</u>

  • Reading a Periodic Table
  • Periodic Trends
  • Ionization Energy - energy required to remove an electron from a given element
  • Coulomb's Law
  • Shielding Effect
  • Z-effective and Forces of Attraction

Explanation:

The Periodic Trend for 1st Ionization Energy is increasing up and to the right. That means He would have the highest I.E and therefore take the most amount of energy to remove an electron.

Potassium and Gallium are both in Period 4. Potassium is element 19 and Gallium is element 31.

Potassium's electron configuration is [Ne] 4s¹ and Gallium's electron configurations is [Ne] 4s²3d¹⁰4p¹. Since both are in Period 4, they have the same number of core e⁻. Therefore, the shielding effect is the same.

However, since Gallium is element 31, it has 31 protons compared to Potassium, which is element 19 and has 19 protons. Gallium would have a greater Zeff than Potassium as it has more protons. Therefore, the FOA between the electrons and nucleus of Ga is much stronger than that of K. Thus, Ga requires <em>more</em> energy to overcome those FOA to remove the 4p¹ e⁻. Since K has less protons, it will have a smaller Zeff and thus less FOA between the e⁻ and nucleus, requiring <em>less</em> energy to remove the 4s¹ e⁻.

7 0
3 years ago
How many grams of O₂ are required to react completely with 14.6 g of Na to form sodium oxide, Na₂O?
Bad White [126]

The balanced chemical reaction is :

O_2 + 4Na \ -> \ 2Na_2O

Number of moles of Na, n = \dfrac{14.6}{23} = 0.635 \  mol .

Now, from balance chemical reaction we can see that 1 mole of oxygen reacts with 4 moles of sodium.

So, number of moles of oxygen are :

n = \dfrac{0.635}{4}\  mole

So, amount of oxygen required is :

m = \dfrac{0.635 \times 32}{4}\  gm\\\\m = 5.08 \ gm

Therefore, 5.08 gram of oxygen will react with 14.6 gram of sodium.

7 0
3 years ago
Convection currents in the mantle contribute to tectonic plate movement. What is a convection current?
RUDIKE [14]

Answer:

A.) the transfer of energy through a solid, such as the Earth’s crust

I hope this helps! ^-^

5 0
2 years ago
Objects that vibrate make energy. Which
kap26 [50]

Answer:

A sound

Explanation:

7 0
3 years ago
Read 2 more answers
In an addition reaction to an alkene the pi bond plays the role of
stealth61 [152]
Nucleophile electrophile
7 0
3 years ago
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