<span>Hydrogen
gas (H2) can be found in trace amounts in Earth’s atmosphere.
a. Hydrogen is found in acids.
b. Hydrogen gas is highly flammable.
c. Hydrogen reacts with oxygen to form water.
These are true, but they all describe chemical properties
of Hydrogen, not physical properties.
d. Hydrogen gas
is less dense than oxygen gas.
Yes ! This is a physical property of Hydrogen.
</span>
Answer:
The total number of Cl atoms in 150mL of liquid CCl4 is 3.73*10²⁴.
Explanation:
First you must determine the mass of CCL4 present in 150mL of CCl4. Density is a quantity that allows us to measure the amount of mass in a certain volume of a substance, whose expression for its calculation is the quotient between the mass of a body and the volume it occupies:

In this case, the density value of d = 1.589 g/mL. Then, being the volume equal to 150 mL, the value of the mass can be calculated as:
mass= density*volume
mass=1.589 g/mL * 150 mL
mass= 238.35 g
Now, being the molar mass of CCl4 154 g/mol, the number of moles that 238.35 g represents is calculated as:

moles= 1.55
1 mole of the compound CCl4 contains 4 moles of Cl. Then, using a simple rule of three, it is possible to calculate the number of moles of Cl that 1.55 moles of CCl4 contain:

moles of Cl= 6.2
Avogadro's Number or Avogadro's Constant is called the number of particles that make up a substance (usually atoms or molecules) and that can be found in the amount of one mole of said substance. Its value is 6.023*10²³ particles per mole. Avogadro's number applies to any substance. In this case it can be applied as follows: if 1 mole of Cl contains 6.023*10²³ atoms, 6.2 moles of Cl how many atoms does it contain?

atoms of Cl= 3.73*10²⁴
<u><em>The total number of Cl atoms in 150mL of liquid CCl4 is 3.73*10²⁴.</em></u>
Visible light waves are the only electromagnetic waves we can see has the longest wavelength
<span>The amount of dissolved oxygen in water may decrease
because of the increase in organic matter in the water. <span>Aquatic organisms breathe and use oxygen. Large amounts of
oxygen are consumed by the decomposition of bacteria (when there are large
amounts of dead matter to decompose, there will be a significant number of
bacteria). Examples: dead organic matter (algae), wastewater, garden waste,
oils and fats, all this results in a decrease in dissolved oxygen in the water.</span></span>