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Lady_Fox [76]
3 years ago
8

what is the kinetic energy of the emitted electrons when cesium is exposed to uv rays of frequency 1.4×1015hz?

Chemistry
1 answer:
Anika [276]3 years ago
7 0
<span>The equation you used is KE=hv-hv0, where h=6.63*10^-34 (constant). You multiply h by 1.5*10^15. Multiply h by the threshold freq of cesium (from part A). Subtract the second answer from the first answer, and you get the kinetic energy. Hope this helps.</span>
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Which of the following chemical formula show an iconic compound
BaLLatris [955]
This question comes with this list of answer choices:

<span>A. CO₂

B.N₂O

C.NaCl

</span><span> D.C₆H₁₂O₆
</span>

Answer: option C.NaCl

Justification.

1) When two diferent elements join together chemically they can form either a covalent bond or a ionic bond.

2) When the bonds are covalents the compound is called covalent, when the bonds are ionics the compound is called ionic.

3) To predict whether the compound is ionic or covalent, you must see the electronegativities of the elements.

4) Ionic compounds require the formation of ions, a posititve ion and a negative ion. The positive ion is formed when the element loses one or more electrons. The negative ion is formed when the element gains one or more electrons.

Then, in the formation of a ionic compound it is implicit the exchange of electrons (one element gains the electrons that the other lose) and this is possible, when the difference in electronegativities are high enough.

5) So, you must look at the electronegativities to make your prediction. In the given options, the compounds of the options A, B and D are between non-metals. Then, you can predict that their electronegativities are not as much differet as to form ions. They will form covalent bonds.


6) Being sodium and chloride a metal and non-metal, you can expect that their electronegativities differ quite enough to form the ionic bond (this is not true for any pair of non-metal and metal elements, but being them the only pair of metal - non metal elements, this is the only option).

This leads to the conclusion that the NaCl formula shows an ionic compound, and is the answer.

5 0
3 years ago
What is the density of an object that has a mass of 149. 8 g and displaces 12. 1 ml of water when placed in a graduated cylinder
kozerog [31]

Answer:

<h2>12.38 g/mL</h2>

Explanation:

The density of a substance can be found by using the formula

d =  \frac{m}{v}  \\

m is the mass

v is the volume

From the question

m = 149.8 g

v = 12.1 mL

We have

d =  \frac{149.8}{12.1}  = 12.380165... \\

We have the final answer as

<h3>12.38 g/mL</h3>

Hope this helps you

4 0
2 years ago
How many ions are present if 2.0 moles of hno3 are completely dissolved in water?
Arte-miy333 [17]
Nitric acid(HNO3) is a strong acid so most of its component will dissociate into an ion form. When dissolved into water, nitric acid will have this reaction
HNO3= 1 H^{+} + NO3^{-} 

For every 1 mol of HNO3, there will be 1 mol of H+ ion and NO3- ion formed, which makes a total of 2 ions(degree of dissociation = 2). 
Then for 2 moles of HNO3 it would be: 2 moles * 2= 4 moles of ion
5 0
3 years ago
Read 2 more answers
In an experiment, a student wants to increase the rate of a reaction that involves gases. Which change to the reactants would ac
Ivahew [28]

Answer:

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Explanation:

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Thus, when the volume of reactants is decreased, the pressure increases.This increase in pressure has the same effect as increase in concentration. Hence, the rate of forward reaction increases.

4 0
2 years ago
Heat transfer by conduction occurs when
Stolb23 [73]
It is none of the three. Conduction occurs when a heat source directly is touching an object. 

Explanation: Number 1 is convection. Key term: convection currents. Number 2 is radiation, as radiation can pass through space. Number 3 is just explaining a part of the convection current.
7 0
3 years ago
Read 2 more answers
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