Answer:
Alkali metals
Explanation:
The alkali metals are a group of metallic elements which are present in the first group of the periodic table. In other words, they are present in group 1 of the periodic table. These elements have one electron in their valence shell, the reason why they are placed in group 1.
They ionize by losing one electron to achieve the configuration of the nearest Noble gas or inert gas. Because they need to offset only one electron in their outermost shell, they are very chemically reactive and hence rarely occur in the free state.
Examples of elements in this group include lithium, potassium and sodium. They each have one electron only in their outermost shells.
Answer:
The correct answer is -
FALSIFIABLE:
Aloe vera gel can heal wounds by boosting cell renewal.
Drinking aloe juice can reduce the risk of lung cancer.
NON-FALSIFIABLE:
Aloe vera gel is the best natural skin moisturizer.
Aloe vera juice tastes better than carrot juice.
Explanation:
Falsifiable is the ability or chances of any hypothesis, claim or statement to be proved wrong. In such a hypothesis, it is possible to carry an experimental observation that disproves the idea in claim or question.
In the given examples
Aloe vera gel can heal wounds by boosting cell renewal.
Drinking aloe juice can reduce the risk of lung cancer.
There is no observation in the favor of the claim so there more likely to be falsifiable whereas, Aloe vera gel is the best natural skin moisturizer.
Aloe vera juice tastes better than carrot juice are more non-falsifiable as these are based on personal choice or experimental observation.
The compound name for H3S5 is hydrosulfide sulfanide sulfide
Answer:
This means the amount of PbCrO4 will precipitate first, with a [Pb^2+] concentration of 1.8*10^-12 M
Explanation:
Step 1: Data given
Molarity of Na2CrO4 = 0.010 M
Molarity of NaBr = 2.5 M
Ksp(PbCrO4) = 1.8 * 10^–14
Ksp(PbBr2) = 6.3 * 10^–6
Step 2: The balanced equation
PbCrO4 →Pb^2+ + CrO4^2-
PbBr2 → Pb^2+ + 2Br-
Step 3: Define Ksp
Ksp PbCrO4 = [Pb^2+]*[CrO4^2-]
1.8*10^-14 = [Pb^2+] * 0.010 M
[Pb^2+] = 1.8*10^-14 /0.010
[Pb^2+] = 1.8*10^-12 M
The minimum [Pb^2+] needed to precipitate PbCrO4 is 1.8*10^-12 M
Ksp PbBr2 = [Pb^2+][Br-]²
6.3 * 10^–6 = [Pb^2+] (2.5)²
[Pb^2+] = 1*10^-6 M
The minimum [Pb^2+] needed to precipitate PbBr2 is 1*10^-6 M
This means the amount of PbCrO4 will precipitate first, with a [Pb^2+] concentration of 1.8*10^-12 M
<u>Answer:</u> The average atomic mass of X is 28.09 amu
<u>Explanation:</u>
Average atomic mass of an element is defined as the sum of masses of each isotope each multiplied by their natural fractional abundance.
Formula used to calculate average atomic mass follows:
.....(1)
Mass of isotope 1 = 27.979 amu
Percentage abundance of isotope 1 = 92.21 %
Fractional abundance of isotope 1 = 0.9212
Mass of isotope 2 = 28.976 amu
Percentage abundance of isotope 2 = 4.70 %
Fractional abundance of isotope 2 = 0.0470
Mass of isotope 3 = 29.974 amu
Percentage abundance of isotope 3 = 3.09 %
Fractional abundance of isotope 3 = 0.0309
Putting values in equation 1, we get:
![\text{Average atomic mass of X}=[(27.979\times 0.9212)+(28.976\times 0.0470)+(29.974\times 0.0309)]](https://tex.z-dn.net/?f=%5Ctext%7BAverage%20atomic%20mass%20of%20X%7D%3D%5B%2827.979%5Ctimes%200.9212%29%2B%2828.976%5Ctimes%200.0470%29%2B%2829.974%5Ctimes%200.0309%29%5D)
Hence, the average atomic mass of X is 28.09 amu
