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Advocard [28]
3 years ago
6

What is the atomic number of the following element??

Chemistry
2 answers:
Vinvika [58]3 years ago
7 0

Answer:

91

Explanation:

Alla [95]3 years ago
3 0
91 it always says the number in the top left corner
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The gas in a sealed container has an absolute pressure of 125.4 kilopascals. If the air around the container is at a pressure of
AlexFokin [52]

Answer: C. 25.6 kPa

Explanation:

The Gauge pressure is defined as the amount of pressure in a fluid that exceeds the amount of pressure in the atmosphere.

As such, the formula will be,

PG = PT – PA

Where,

PG is Gauge Pressure

PT is Absolute Pressure

PA is Atmospheric Pressure

Inputted in the formula,

PG = 125.4 - 99.8

PG = 25.6 kPa

The gauge pressure inside the container is 25.6kPa which is option C.

4 0
3 years ago
If a radioactive isotope has a half-life of 26.5 days, how many days does it take for a sample of the isotope to decrease by 35.
dangina [55]

Answer:

16.5 days

Explanation:

Given that:

Half life = 26.5 days

t_{1/2}=\frac {ln\ 2}{k}

Where, k is rate constant

So,  

k=\frac {ln\ 2}{t_{1/2}}

k=\frac {ln\ 2}{26.5}\ days^{-1}

The rate constant, k = 0.02616 days⁻¹

Using integrated rate law for first order kinetics as:

[A_t]=[A_0]e^{-kt}

Where,  

[A_t] is the concentration at time t

[A_0] is the initial concentration

Given:

35.0 % is decomposed which means that 0.35 of [A_0] is decomposed. So,

\frac {[A_t]}{[A_0]} = 1 - 0.35 = 0.65

t = 7.8 min

\frac {[A_t]}{[A_0]}=e^{-k\times t}

0.65=e^{-0.02616\times t}

<u>t = 16.5 days.</u>

7 0
4 years ago
Ca(s)+2hno3(aq)→ca(no3)2(aq)+h2(g) identify the oxidizing agent.
aleksandr82 [10.1K]

To find for the oxidizing agent, first let us write the half reactions of this complete chemical reaction:

Ca = Ca2+ + 2e- <span>
2 H+ + 2e- = H2</span>

 

The oxidizing agent would be the substance of the element that is reduced. We know that an element is reduced when an electron is added to it. In this case, the element being reduced is H. Therefore the oxidizing agent is HNO3.

 

Answer:

<span>HNO3</span>

8 0
3 years ago
Read 2 more answers
Which of the following equations are correctly balanced?
AlladinOne [14]

i think it's I

I was confused by IV then search on gg and it said ZnSO4 should be Zn2SO4 instead but still im not sure Zn2SO4 is real

3 0
3 years ago
Which statement justifies that hydrogen peroxide (H2O2) is a polar molecule?
Rudik [331]
To determine whether a compound is polar or nonpolar you have to take into account:

1) formation of dipoles due to the difference in electronegativities of the atoms

2) shape of the molecule to conclude whether there is a net dipole momentum.

You already, likely, know that the electronegativities of H and O are significatively different, being O more electronegative thatn H. So, you can conclude easilty that the electrons are atracted more by O than by H, thus creating two dipoles H→O

Regarding the shape, it may appear that the molecule is symmetrical, which would lead to the cancellation of the two dipoles. But that is not the true. The H2O2 is not symmetrical.

The lewis structure just show this shape

      **   **
H - O - O - H
      **   **

which is what may induce to think that the molecule is symmetrical, leading to the misconception that it is nonpolar.

But in a three dimensional arrangement you could see that the hydrogens are placed in non symmetrical positions, which leads to the formation of a net dipole momentum, and thus to a polar molecule.

The fact that H2O2 is a polar compound is the reason why it can be mixed with water and the H2O2 that you buy in the pharmacy is normally a solution in water.

So, the hydrogen peroxide is polar because the hydrogens are not placed symmetrically in the molecule, which result in a net dipole momentum.
4 0
4 years ago
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