Answer: Mass of gas is 0.001 pounds.
Explanation:
Density is defined as the mass contained per unit volume.
Given : Mass of gas = ?
Density of gas = 
Volume of gas = 389 ml = 0.389 L (1L=1000ml)
Putting in the values we get:
(1g =0.002 lb)
Thus the mass of gas is 0.001 pounds.
Answer: -
C) because the moon rotates once on its axis in the same time that it takes to revolve around the earth
Explanation: -
The moon rotates about it's axis one full time at about the same time as it takes to rotate around the earth.
This leads to only one side of the moon always appearing to Earth, called the near side.
One side of the moon is always not seen from the earth. It is called the far side of the moon.
Thus we can never see the far side of the moon because the moon rotates once on its axis in the same time that it takes to revolve around the earth
Answer:
pH = 7.46
Explanation:
2H₂O ⇄ H₃O⁺ . OH⁻ Kw = [H₃O⁺] . [OH⁻]
[H₃O⁺] = [OH⁻]
√0.12×10⁻¹⁴ = [H₃O⁺] → 3.46×10⁻⁸ M
- log [H₃O⁺] = pH
- log 3.46×10⁻⁸ = pH → 7.46
This problem is honestly, very easy. Just grab a periodic table and find the element in Group 1 and Period 7. But first, let's discuss how the elements are arranged systematically in a periodic table. There are a lot of scientists who contributed to it, but the most famous one is Dimitri Mendeleev. He arranged the elements according to their atomic number. The elements starts from 1 which is Hydrogen up to the heaviest known elements which is Oganesson with an atomic number of 118. As you can observe, there is a gap between groups 3 and 4. This is done so that the periodic table does not take too much space horizontally. Thus, they are just placed at the bottom. These elements are called lanthanides (upper row) and actinides (lower row). The rows in the periodic table are called groups, and the columns are called periods.
Now, the element at the lower left corner (Group 1, Period 7) is Francium, abbreviated as Fr. It has an atomic number of 87. Some elements are actually synthesized, but Francium is a naturally occurring radioactive element. It was discovered by Marguerite Perey in France.
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