Ernest Rutherford
J. J Thomson
Explanation:
<u>Ernest Rutherford</u>
In 1911, Ernest Rutherford, a New Zealand chemist performed the gold foil experiment where he gave the modelling of the atom a boost.
Experiment
In his experiment, he bombarded a thin gold foil with alpha particles generated from a radioactive source. He found that most of the alpha particles passed through the gold foil while a few of them were deflected back.
Discovery and reflection on the atomic theory
To account for his observation, Rutherford suggested an atomic model in which an atom has small positively charged center where nearly all the mass is concentrated.
<u>J. J Thomson</u>
Experiment
In 1897 J.J Thomson performed experiments using the gas discharge tube that led to the discovery of the electrons. He called them cathode rays because they originate from the cathode and exits at the anode.
Discovery and reflection on the atomic theory
From his experiment on the gas discharge tube, Thomson was able determine the properties of cathode rays some of which are:
- they move in a straight line
- they possess kinetic energy
- they attract positive charges and repels negative charges
Using his observation, he proposed the plum pudding model of the atom where it is made up of entirely electrons.
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Answer:
The correct answer is B) it helps to ensure the result are consistent and repeatable.
Explanation:
Scientist generally repeat an experiment if he or she did not make a mistake in the first one to compare the results of two experiment, if there is no difference in the result or values obtainted from the observation of two experiment. he or she become sure that experiment was done in a right way because if there is some error made when experiment was carried out then the result of two same experiment would be different.
The answer for the following mention bellow.
- <u><em>Therefore the final temperature of the gas is 260 k</em></u>
Explanation:
Given:
Initial pressure (
) = 150.0 kPa
Final pressure (
) = 210.0 kPa
Initial volume (
) = 1.75 L
Final volume (
) = 1.30 L
Initial temperature (
) = -23°C = 250 k
To find:
Final temperature (
)
We know;
According to the ideal gas equation;
P × V = n × R ×T
where;
P represents the pressure of the gas
V represents the volume of the gas
n represents the no of moles of the gas
R represents the universal gas constant
T represents the temperature of the gas
We know;
= constant
×
= 
Where;
(
) represents the initial pressure of the gas
(
) represents the final pressure of the gas
(
) represents the initial volume of the gas
(
) represents the final volume of the gas
(
) represents the initial temperature of the gas
(
) represents the final temperature of the gas
So;
= 
(
) =260 k
<u><em>Therefore the final temperature of the gas is 260 k</em></u>
<u><em></em></u>
<u>Answer:</u> The amount of heat required to warm given amount of water is 470.9 kJ
<u>Explanation:</u>
To calculate the mass of water, we use the equation:

Density of water = 1 g/mL
Volume of water = 1.50 L = 1500 mL (Conversion factor: 1 L = 1000 mL)
Putting values in above equation, we get:

To calculate the heat absorbed by the water, we use the equation:

where,
q = heat absorbed
m = mass of water = 1500 g
c = heat capacity of water = 4.186 J/g°C
= change in temperature = 
Putting values in above equation, we get:

Hence, the amount of heat required to warm given amount of water is 470.9 kJ
1 is the number of unpaired electrons in the outer subshell of a Cl atom