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just olya [345]
3 years ago
9

Celery stalks that are immersed in fresh water for several hours become stiff and hard. similar stalks left in asalt solution be

come limp and soft. from this we can deduce that the cells of the celery stalks are
Chemistry
1 answer:
galina1969 [7]3 years ago
4 0
Plasmolysed because of osmosis as the salt solution has lower water potential than the cells of the stalk
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In an experiment to study the photoelectric effect, a scientist measures the kinetic energy of ejected electrons as afunction of
crimeas [40]

Answer:

a) v₀ = 4.41 × 10¹⁴ s⁻¹

b) W₀ = 176 KJ/mol of ejected electrons

c) From the graph, light of frequency less than v₀ will not cause electrons to break free from the surface of the metal. Electron kinetic energy remains at zero as long as the frequency of incident light is less than v₀.

d) When frequency of the light exceeds v₀, there is an increase of electron kinetic energy from zero steadily upwards with a constant slope. This is because, once light frequency exceeds, v₀, its energy too exceeds the work function of the metal and the electrons instantaneously gain the energy of incident light and convert this energy to kinetic energy by breaking free and going into motion. The energy keeps increasing as the energy and frequency of incident light increases and electrons gain more speed.

e) The slope of the line segment gives the Planck's constant. Explanation is in the section below.

Explanation:

The plot for this question which is attached to this solution has Electron kinetic energy on the y-axis and frequency of incident light on the x-axis.

a) Wavelength, λ = 680 nm = 680 × 10⁻⁹ m

Speed of light = 3 × 10⁸ m/s

The frequency of the light, v₀ = ?

Frequency = speed of light/wavelength

v₀ = (3 × 10⁸)/(680 × 10⁻⁹) = 4.41 × 10¹⁴ s⁻¹

b) Work function, W₀ = energy of the light photons with the wavelength of v₀ = E = hv₀

h = Planck's constant = 6.63 × 10⁻³⁴ J.s

E = 6.63 × 10⁻³⁴ × 4.41 × 10¹⁴ = 2.92 × 10⁻¹⁹J

E in J/mol of ejected electrons

Ecalculated × Avogadros constant

= 2.92 × 10⁻¹⁹ × 6.023 × 10²³

= 1.76 × 10⁵ J/mol of ejected electrons = 176 KJ/mol of ejected electrons

c) Light of frequency less than v₀ does not possess enough energy to cause electrons to break free from the metal surface. The energy of light with frequency less than v₀ is less than the work function of the metal (which is the minimum amount of energy of light required to excite electrons on metal surface enough to break free).

As evident from the graph, electron kinetic energy remains at zero as long as the frequency of incident light is less than v₀.

d) When frequency of the light exceeds v₀, there is an increase of electron kinetic energy from zero steadily upwards with a constant slope. This is because, once light frequency exceeds, v₀, its energy too exceeds the work function of the metal and the electrons instantaneously gain the energy of incident light and convert this energy to kinetic energy by breaking free and going into motion. The energy keeps increasing as the energy and frequency of incident light increases and electrons gain more speed.

e) The slope of the line segment gives the Planck's constant. From the mathematical relationship, E = hv₀,

And the slope of the line segment is Energy of ejected electrons/frequency of incident light, E/v₀, which adequately matches the Planck's constant, h = 6.63 × 10⁻³⁴ J.s

Hope this Helps!!!

5 0
3 years ago
C12H22011+1202-->12CO2+11H20
kogti [31]

Answer:

0.185moles

Explanation:

Given parameters:

Volume of O₂  = 49.8L

Unknown:

Number of moles of sucrose required  = ?

Solution:

We can assume that the reaction takes place at standard temperature and pressure.

From this, we can find the number of moles of oxygen that reacted and extrapolate to that of sucrose.

Chemical equation;

           C₁₂H₂₂0₁₁  +  120₂   →   12CO₂   +   11H₂0

Number moles  = \frac{volume of gas}{22.4}   at STP

Number of moles of oxygen gas = \frac{49.8}{22.4}   = 2.22moles

           12 moles of oxygen gas combines with  1 mole of sucrose

       2.22 moles of oxygen gas will combine with \frac{2.22}{12}   = 0.185moles

4 0
3 years ago
Explain whether nitrogen atoms will form bonds with other atoms
iren2701 [21]
The closer the atoms are the more the nitrogen will be come bigger or the oppisite

3 0
3 years ago
Metals and nonmetals all lesson explanation for class 8​
WINSTONCH [101]

Answer:

Metalloids elements whose properties are intermediate between those of metals and solid nonmetals or semiconductors.

Some examples:

Chemical element.

Boron.

Semiconductor.

Arsenic.

Silicon.

Selenium.

Antimony.

Germanium.

7 0
3 years ago
Which of the following is an example of CHEMICAL weathering? (select all
larisa86 [58]
Rust on a rock that contains iron
Mineral absorbs water and changes into a new substance
5 0
3 years ago
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