Answer:Silicon
Explanation:
Silicon - Element information, properties and uses | Periodic Table.
Royal Society of Chemistry › 14 › si...
Silicon - Element information, properties and uses | Periodic Table
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Answer:
1.146 x 10⁴ year.
Explanation:
- The decay of carbon-14 is a first order reaction.
- The rate constant of the reaction (k) in a first order reaction = ln (2)/half-life = 0.693/(5730 year) = 1.21 x 10⁻⁴ year⁻¹.
- The integration law of a first order reaction is:
<em>kt = ln [A₀]/[A]</em>
<em></em>
k is the rate constant = 1.21 x 10⁻⁴ year⁻¹.
t is the time = ??? years.
[A₀] is the initial percentage of carbon-14 = 100.0 %.
[A] is the remaining percentage of carbon-14 = 1/4[A₀] = 25.0 %.
∵ kt = ln [Ao]/[A]
∴ (1.21 x 10⁻⁴ year⁻¹)(t) = ln (100.0%)/[25.0 %]
(1.21 x 10⁻⁴ year⁻¹)(t) = 1.386.
∴ <em>t </em>= 1.386/
(1.21 x 10⁻⁴ year⁻¹) = <em>1.146 x 10⁴ year.</em>
Answer:
We need 4.28 grams of sodium formate
Explanation:
<u>Step 1:</u> Data given
MW of sodium formate = 68.01 g/mol
Volume of 0.42 mol/L formic acid = 150 mL = 0.150 L
pH = 3.74
Ka = 0.00018
<u>Step 2:</u> Calculate [base)
3.74 = -log(0.00018) + log [base]/[acid]
0 = log [base]/[acid]
0 = log [base] / 0.42
10^0 = 1 = [base]/0.42 M
[base] = 0.42 M
<u>Step 3:</u> Calculate moles of sodium formate:
Moles sodium formate = molarity * volume
Moles of sodium formate = 0.42 M * 0.150 L = 0.063 moles
<u>Step 4:</u> Calculate mass of sodium formate:
Mass sodium formate = moles sodium formate * Molar mass sodium formate
Mass sodium formate = 0.063 mol * 68.01 g/mol
Mass sodium formate = 4.28 grams
We need 4.28 grams of sodium formate
<em>Answer:</em>
Symbol = I
<em>Explanation:</em>
<em>Isotopes</em> are those substances which have same atomic number (Numbers of protons) and different masses (Number of proton + numbers of neutrons).
- Iodine also have many isotopes like
<em>Iodine-125</em> that contain 53 protons, 72 neutrons.
<em>Iodine-128</em> that contain 53 protons, 75 neutrons.
<em>Iodine-129 </em> that contain 53 protons, 76 neutrons.
<em>Iodine-131</em> that contain 53 protons, 78 neutrons.
<em>Summary:</em>
- Here the Iodine-131 is correct answer of this question.
