The mass number of aluminium is 26 and the atomic number of aluminium is 13.
The number of neutrons is given by the difference between the mass number and number of protons.
number of neutrons = mass number - number of protons
Number of protons = 13
Mass number of Aluminium = 26
Therefore number of neutrons = 26-13 = 13.
The atomic number of thorium is 90 and the mass number of thorium is 230 as given in the question
atomic number = number of electrons = number of protons
Therefore the number of electrons in thorium 230 = 90
Number of protons in thorium 230 = 90
Number of neutrons = Mass number - number of protons = 230-90 = 140
Your measurement implies that the range of answers is 128.6 mL to 128.8 mL.
If you do not state explicitly the range of uncertainty (e.g., ± 0.5 mL), the <em>implied range of uncertainty</em> is ±1 in the last significant digit.
Thus, a reading of 128.7 mL implies that the volume is 128.7 mL ± 0.1 mL.
A 3.4 × 10⁶ L swimming pool must have a mass of 1.0 × 10⁷ mg Cl₂ to maintain a concentration of 3.0 ppm.
<h3>What is "ppm"?</h3>
"ppm" of "parts per million" is a unit of concentration equivalent to milligrams of solute per liters of solution.
A pool must maintain a chlorine concentration of 3.0 ppm (3.0 mg/L). The mass of chlorine in 3.4 × 10⁶ L is:
3.0 mg Cl₂/L × 3.4 × 10⁶ L = 1.0 × 10⁷ mg Cl₂
A 3.4 × 10⁶ L swimming pool must have a mass of 1.0 × 10⁷ mg Cl₂ to maintain a concentration of 3.0 ppm.
Learn more about ppm here: brainly.com/question/13395702
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Is this the full question?
<span>Heat that flows by conduction is the transfer of thermal energy between substances in contact. For this to happen, what must occur?
A) The two systems must be the same temperature.
B) The two systems must not be touching each another.
C) One system must have higher kinetic energy than the other system.
D) The thermal energy of one system must be the same as the thermal energy of the other system.</span>
During this process. A. Solid turns directly into a Gas.
