Answer: Please see answer below
Explanation:
Mecury vapor lamp is better to use than Sodium vapor light, this is because because
---The Filaments of the lamp in sodium emit fast moving electrons, which causes valence electrons of the sodium atoms to excite to higher energy levels which when electrons after being excited, relax by emitting yellow light which concentrates on the the monochromatic bright yellow part of the visible spectrum which is about 580-590 or about (589nm) which will fall incident on the calibrations making it difficult to see
While
In Mercury vapor lamp, The emitted electrons from the filaments, after having been excited by high voltage, hit the mercury atoms but the excited electrons of mercury atoms relax and emits an ultraviolet uv invisible lights falling on the mecury vapour lamp to produce white light covering a wide range of (380-780 nm) which is visible that is why it is used for calibrations purposes in lightening applications.
Polarity is the chemical property based on the electric charge and orientation of the poles. Al−O>H−Br>As−S is arranged in decreasing order of polarity. Thus, option d is correct.
<h3>What is polarity?</h3>
Polarity is a chemical property of the distribution of the electrical charges over their respective atom in the molecule joined by the bonds. The relation between the polarity and the difference in electronegativity is directly proportional.
The electronegativity difference between the elements are:
- Al−O = 1.8
- H−Br = 0.8
- As−S = 0.4
As the electronegativity difference between Al−O = 1.8 is the highest it will have the highest polarity followed by H−Br = 0.8, and As−S = 0.4, with the lowest polarity.
Therefore, option D. Al−O>H−Br>As−S is arranged in decreasing order of polarity.
Learn more about electronegativity here:
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KE=1/2*mass*velocity^2
So u do 1/2 * 1 * 30^2
1/2 * 1 * 900
= 450kgm/s
P.s. I'm not sure if I would have to convert kg to g.
Anyways hope this helped
Answer:
B. PROTONS EXHIBIT STRONGER PULL ON OUTER f ORBITALS
Explanation:
Lanthanide contraction is the greater than normal decrease in the ionic radius of the lanthanide series from atomic number 57 to atomic number 71. This decrease is rather not expected of the ionic radii of these elements and they result in the greater decrease in the subsequent series of the lanthanides from the atomic number 72. The cause of which is as a result of the poor shielding effects of the nuclear charge around the electrons of the f orbitals. So therefore, protons are strongly pulled out of the 4f orbital and as a result of the poor shielding effect which causes the electrons of the 6s orbitals to be drawn more closer to the nucleus and hence resulting in a smaller atomic radii. It is worthy to note that the shielding effects of the inner electrons decreasing from s orbital to the f orbital; that is s > p > d > f. So from the decrease in the shielding effects from s to the f orbitals, lanthanide contraction results from the inability of the orbitals far away from s like the 4f orbiatls to shield the outermost shells of the lanthanide elements. So the cause of lanthanide contraction is the action of the protons which strongly pull the electrons of the f orbitals because of the poor shielding effects due to the distance of this orbital from the nucleus.
