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andrew-mc [135]
3 years ago
11

Why are there only two elements in the first period of the periodic table?

Chemistry
2 answers:
noname [10]3 years ago
8 0
The reason why there are only two elements in the first period of the periodic table is because hydrogen is the main reactant while helium is the main non-reactant.
Solnce55 [7]3 years ago
5 0
The first period has less elementsthan any other periods in the periodic table. There are only two elements in the first period: hydrogen and helium. We can explain why there is lesselements in the first row in modern theories of atomic structure. ... Theseelements can only hold two electrons, both in the 1s orbital
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Why is unit of pressure called a derived unit ?? 2) how do you measure the volume of milk?<br>​
trasher [3.6K]

1. Unit of pressure called a derived unit because it is a combination of base units (kg·m^-1·s^·2).

2. We measure the volume of milk by a instrument called Milk Lactometer.

4 0
3 years ago
There is 35 mg of sodium in a can of Coke. You determine it to be 28 mg. What is your percent error?
natali 33 [55]

Answer:

The answer is

<h2>20 %</h2>

Explanation:

The percentage error of a certain measurement can be found by using the formula

P(\%) =  \frac{error}{actual \:  \: number}  \times 100\% \\

From the question

actual volume = 35 mg

error = 35 - 28 = 7

The percentage error is

P(\%) =  \frac{7}{35}  \times 100 \\  =  \frac{1}{5}  \times 100 \\  =  20

We have the final answer as

<h3>20 %</h3>

Hope this helps you

8 0
3 years ago
Read 2 more answers
A 7.32 g sample of copper is contaminated with 0.81 g of zinc. Suppose an atomic mass measurement was performed on this sample.
sergejj [24]
Hope it cleared your doubt.

5 0
3 years ago
Please help! Thanks :D
Digiron [165]
<h3>1</h3>

Species shown in bold are precipitates.

  • Ca(NO₃)₂ + 2 KOH → Ca(OH)₂ + 2 KNO₃
  • Ca(NO₃)₂ + Na₂C₂O₄ → CaC₂O₄ + 2 NaNO₃
  • Cu(NO₃)₂ + 2 KI → CuI₂ + 2 KI
  • Cu(NO₃)₂ + 2 KOH → Cu(OH)₂ + 2 KNO₃
  • Cu(NO₃)₂ + Na₂C₂O₄ → CuC₂O₄ + 2 NaNO₃
  • Ni(NO₃)₂ + 2 KOH → Ni(OH)₂ + 2 KNO₃
  • Ni(NO₃)₂ + Na₂C₂O₄ → NiC₂O₄ + 2 NaNO₃
  • Zn(NO₃)₂ + 2 KOH → Zn(OH)₂ + 2 KNO₃
  • Zn(NO₃)₂ + Na₂C₂O₄ → ZnC₂O₄ + 2 NaNO₃

<h3>2</h3>

A double replacement reaction takes place only if it reduces in the concentration of ions in the solution. For example, the reaction between Ca(NO₃)₂ and KOH produces Ca(OH)₂. Ca(OH)₂ barely dissolves. The reaction has removed Ca²⁺ and OH⁻ ions from the solution.

Some of the reactions lead to neither precipitates nor gases. They will not take place since they are not energetically favored.


<h3>3</h3>

Compare the first and last row:

Both Ca(NO₃)₂ and Zn(NO₃)₂ react with KOH. However, between the two precipitates formed, Ca(OH)₂ is more soluble than Zn(OH)₂.

As a result, add the same amount of KOH to two Ca(NO₃)₂ and Zn(NO₃)₂ of equal concentration. The solution that end up with more precipitate shall belong to Zn(NO₃)₂.


<h3>4</h3>

Compare the second and third row:

Cu(NO₃)₂ reacts with KI, but Ni(NO₃)₂ does not. Thus, add equal amount of KI to the two unknowns. The solution that forms precipitate shall belong to Cu(NO₃)₂.

8 0
3 years ago
Condensation is a process for which a. ΔG is negative at high temperature but positive at low temperature. b. ΔH and ΔS are nega
IgorC [24]

Answer:

b. ΔH and ΔS are negative at all temperatures .

Explanation:

During the process of condensation ,

The gaseous state convert to liquid state ,

Hence , the entropy of the system reduces , i.e. , the randomness decreases .

And the value for entropy is negative ,

hence ,

Δ S = negative ,

Δ H = negative ,

Since ,

The heat is releasing from system .

hence , the most appropriate option will be ΔH and ΔS are negative at all temperatures .

7 0
3 years ago
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