Well the width is 0.20 meters. Since there are a hundred centimeters in a meter, we just have to move the decimal point two times to the right to get a 20 centimeter width.
A chemical reaction that has a positive g is best described as endergonic.
<span>The substance that is produced at the cathode during the electrolysis of a mixture of molten calcium bromide, cabr2(I), and molten magnesium iodide, mgi2(I), can be expressed as Ca2+ + 2eâ’ --> Ca. At the anode, the substance can be expressed as 2Brâ’ â’ 2eâ’ --> Br2. At the cathode for magnesium iodide can be expressed as Mg2+ + 2 eâ’ --> Mg, and 2 Iâ’ â’ 2 eâ’ --> I2 at the anode.</span>
<u>Answer: </u>The correct statement is X is the effective nuclear charge, and it increases across a period.
<u>Explanation:</u>
We are given that:
X = number of protons − number of core electrons
Effective nuclear charge is defined as the actual nuclear charge (Z = number of protons) minus the screening effect caused by the electrons present between nucleus and valence electrons. These electrons are the core electrons.
The formula used for the calculation of effective nuclear charge given by Slater is:

where,
= effective nuclear charge
Z = atomic number or actual nuclear charge or number of protons
= Screening constant
The effective nuclear charge increases as we go from left to right in a period because nuclear charge increases with no effective increase in screening constant.
Hence, the correct answer is X is the effective nuclear charge, and it increases across a period.