Answer:
31
Explanation:
Given:
U=3
X=4
Y=7
u + xy
Substitute the given values to the equation:
3 + (4)(7)
3 + 28
31
Answer:
Option b. Effective nuclear charge increases as we move to the right across a row in the periodic table
Explanation:
The <em>effective nuclear charge </em>is a measure of how strong the protons in the nucleus of an atom attract the outermost electrons of such atom.
The <em>effective nuclear charge</em> is the net positive charge experienced by valence electrons and is calculated (as an approximation) by the equation: Zeff = Z – S, where Z is the atomic number and S is the number of shielding electrons.
The shielding electrons are those electrons in between the interesting electrons and the nucleus of the atom.
Since the shielding electrons are closer to the nucleus, they repel the outermost electrons and so cancel some of the attraction exerted by the positive charge of the nucleus, meaning that the outermost electrons feel less the efect of attraction of the protons. That is why in the equation of Zeff, the shielding electrons (S) subtract the total from the atomic number Z.
The <em>effective nuclear charge</em>, then, is responsible for some properties and trends in the periodic table. Here, you can see how this explains the trend of the atomic radius (size of the atom) accross a row in the periodic table.
- As the<em> effective nuclear charge</em> is larger, in a same row of the periodic table, the shielding effect is lower, the outermost electrons are more strongly attracted by the nucleus, and the size of the atoms decrease. That is why as we move to the right in the periodic table, the size of the atoms decrease.
Answer:
(a). The speed of electron is 
.
(b). The radius of electron is 
Explanation:
Given that,
Length = 2.5 cm
Distance = 6.0 mm
Magnetic field = 2.1 T
Potential difference = 700 V
(a). We need to calculate the electron's speed
Using formula of speed
Put the value into the formula
(b). We need to calculate the radius of electron
Using formula of centripetal force
Where,
m = mass of electron
v = speed of electron
r = radius
q = charge of electron
B = magnetic field
Put the value into the formula
Hence, (a). The speed of electron is .
(b). The radius of electron is 4.2 cm
Answer: - 25.2 kgm/s
Explanation: The mass of the ball is 0.5kg, and the initial velocity = 10.6m/s.
The final velocity is in opposite direction of the initial hence final velocity (v) = - 19.9 m/s
Impulse = change in momentum = final momentum - initial momentum.
Final momentum = mass × final velocity
Final momentum = - 19.9 × 0.5
Final momentum = - 9.95 kgm/s
Initial momentum = mass × initial velocity
Initial momentum = 0.5 × 10.6 = 5.3kgm/s
Change in momentum = final momentum - initial momentum = - 19.9 - 5.3
Change in momentum = - 25.2 kgm/s
The negative sign implies that the change in momentum is the opposite direction relative to the first.
