Which of the following best describes chemical reactions? Question 1 options: A)
ID: 112815 • Letter: W
Question
Which of the following best describes chemical reactions?
Question 1 options:
A)
They change heavier elements into lighter ones.
B)
They involve only the nuclei of an atom.
C)
They involve only the electrons of an atom or molecule.
D)
They change lighter elements into heavier ones.
Dr.'s Kelvin and Helmholtz suggested _________________ as possible energy source to explain the Sun's current energy output. This was later proved incorrect.
A)
Gravitational Potential Energy
B)
Chemical Reactions
C)
Fusion Reactions
D)
Matter/Antimatter Reactions
The famous equation E=mc2 represents ______________.
A)
the energy of an object traveling at the speed of light
B)
the mass of an object traveling at the speed of light
C)
the amount of mass lost by an object traveling at the speed of light
D)
the amount of mass converted to energy in nuclear reactions
In order for nuclear fusion to occur in the Sun, the density must be _________ and the temperature must be ________.
Which of the following choices best illustrates the net fusion reaction presently occurring in the core of the Sun?
A)
4 1H --> 1 4He + energy + 2 neutrinos
B)
1 2H + 1 3H --> 1 4He + 1 neutron + energy
C)
1 1H + 1 2H --> 1 3He + energy
D)
2 1H --> 1 2H + 1 positron + 1 neutrino
The thermal equilibrium of the Sun requires that the __________ and the __________ must be equal.
Question 6 options:
luminosity, gravity
gravity, gas pressure
energy production, luminosity
temperature, gas pressure
Explanation / Answer
1. C generally we talk about electrons in the case of chemical reactions
2. A yes according to that the source of energy for sun a=was gravitational potential energy
3. D we can say that we use this equation to calculate the energy changes and hence D suites better
5. the reaction that happens in the sun is
4 1H --> 1 4He + energy + 2 neutrinos
6.according to the thermal equilibrium energy production and luminosity must be same
4. temperature is about 15 million Kelvins, the density is 150 times that of water
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