Josh did an experiment recording the changes in temperature in sand and water when exposed to a light source, and then when the
2 answers:
Before going to solve this question first we have to understand specific heat capacity of a substance .
The specific heat of a substance is defined as amount of heat required to raise the temperature of 1 gram of substance through one degree Celsius. Let us consider a substance whose mass is m.Let Q amount of heat is given to it as a result of which its temperature is raised from T to T'.
Hence specific heat of a substance is calculated as-
Here c is the specific heat capacity.
The substance whose specific heat capacity is more will take more time to be heated up to a certain temperature as compared to a substance having low specific heat which is to be heated up to the same temperature.
As per the question John is experimenting on sand and water.Between sand and water,water has the specific heat 1 cal/gram per degree centigrade which is larger as compared to sand.Hence sand will be heated faster as compared to water.The substance which is heated faster will also cools faster.
From this experiment John concludes that water has more specific heat as compared to sand.
Answer:
we can conclude that emissivity of sand will me more than the emissivity of water
Explanation:
As we know that here Source of light is the energy source from which energy is continuously incident on the Sand and Water
So here we know that rate of energy incident on sand and water will be from same source at same rate
Here this energy absorbed by the system is given as
so here the rate of energy absorbed is more sand than water
Also when source is off than rate of energy dissipated by sand is more than the water
So here we can conclude that emissivity of sand will me more than the emissivity of water
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Answer:
B) Na has a lower first ionization energy than Ne.
Explanation:
The atomic number¹ for Na has a value of 11 while in the case of Ne this value is 10. That means that Sodium (Na) has a total number of 11 protons, 11 neutrons and 11 electrons (since it is electrically neutral²). For the case of Neon (Ne) it has 10 protons, 10 neutrons and 10 electrons.
As the atomic number increases, the atomic radius³ shrinks (the orbitals are closer to the nucleus) as a consequence of the electric force. For the case of sodium (Na) the electron in the outermost orbital will experience a lower electric force than the electron placed in the outermost orbital in the atom of Neon (Ne).
Although, the sodium’s atom has more protons and therefore electrons, these eleven electrons will be organized according with the electronic configuration⁴ in the different shells (orbitals) of probabilities of their positions around the atom.
The electronic configuration for Na is:
1s²2s²2p⁶3s¹
The electronic configuration for Ne is:
1s²2s²2p⁶
Since Na needs another orbital to placed its outermost electron, the atomic radius will have a greater value than Ne. The electric force is inversely proportional to the square of the distance between two charged particles, as is established in Coulomb’s law:
(1)
Where q1 and q2 are the charges, is the proportionality constant and r is the distance between the two charges.
Hence, the electron in the outermost orbital of Ne is submitted to a greater electric force according with equation 1, the required energy to remove it (ionization energy⁵) will be greater than in the case of Na (<u>for that case will be the first ionization energy</u>).
¹Atomic number: The number of protons or electrons in an atom.
²Electricaly neutral: All the charges are balanced (same number of positive charges and negative charges).
³Atomic radius: Distance between the center of the nucleus and an electron placed in the outermost orbital for a specific atom.
⁴Electronic configuration: Show how the electrons of an atom will be arranged in different orbitals according with the fact that each orbital has a specific number of electrons that can be held.
⁵Ionization energy: Energy required to remove an electron from an atom.
Key values:
First ionization energy of Na: 495 kJ/mol
First ionization energy of Ne: 2080 kJ/mol
Atomic radius of Na: 2.27 Å
Atomic radius of Ne: 1.54 Å
Atomic number of Na: 11
Atomic number of Ne: 10
Answer:
- <u><em>(b) 1:1</em></u>
Explanation:
<u></u>
<u>1. Formulae:</u>
- E = hf
- E = h.v/λ
- λ = h/(mv)
- E = (1/2)mv²
Where:
- E = kinetic energy of the particle
- λ = de-Broglie wavelength
- m = mass of the particle
- v = speed of the particle
- h = Planck constant
<u><em>2. Reasoning</em></u>
An alha particle contains 2 neutrons and 2 protons, thus its mass number is 4.
A proton has mass number 1.
Thus, the relative masses of an alpha particle and a proton are:
For the kinetic energies you find:
Thus:
From de-Broglie equation, λ = h/(mv)