B.)<span>A doctor would opt for technetium-99m since its brief half-life allows for rapid measurements, while a geologist would select rubidium-87 due to its extended half-life, which provides a more substantial timeframe for dating ancient rocks.</span>
Explanation:
Lewis-dot structure: It illustrates how the atoms in a molecule are bonded together and indicates the presence of unpaired electrons in the molecule.
The molecule in question is, 
Carbon possesses '4' valence electrons, hydrogen has '1' valence electron, and chlorine contains '7' valence electrons.
Consequently, the cumulative count of valence electrons in = 1(1) + 1(4) + 3(7) = 26
Based on the electron-dot structure, there are 8 bonding electrons and 18 non-bonding electrons.
The electron-dot representation for is depicted below.
Next, we need to assess the formal charges on carbon, hydrogen, and chlorine.
The formula for calculating formal charge:
Answer:
CaS, CaBr₂, VBr₅, and V₂S₅.
Explanation:
- The ionic compound must exhibit neutrality; its total charge should equal zero.
- A binary ionic compound is formed from two distinct ions.
Ca²⁺ combines with either Br⁻ or S²⁻ to create binary ionic compounds.
- CaS is created when Ca²⁺ pairs with S²⁻ resulting in the neutral binary ionic compound CaS.
- CaBr₂ results from the combination of one mole of Ca²⁺ with two moles of Br⁻ to form the neutral binary ionic compound CaBr₂.
V⁵⁺ can also unite with either Br⁻ or S²⁻ to produce binary ionic compounds.
- V₂S₅ is formed when two moles of V⁵⁺ bond with five moles of S²⁻ yielding the neutral binary ionic compound V₂S₅.
- VBr₅ is produced by combining one mole of V⁵⁺ with five moles of Br⁻ to form the neutral binary ionic compound VBr₅.
Thus, the empirical formulas for four binary ionic compounds that may be produced are: CaS, CaBr₂, VBr₅, and V₂S₅.
Answer: second option: 1.70 to 1.40
Explanation:
1) pH is defined using the formula pH = - log [H₃O⁺]
2) Given that the initial concentration is x and after doubling it becomes 2x, we calculate:
pHi = - logx
pHf = - log 2x = - log 2 - logx
Thus, pHf - pHi = - log2 - logx - (- logx) = - log2 ≈ - 0.30
⇒ pHi - pHf = 0.30, indicating that the final pH (with twice the hydronium ions) is 0.30 lower than the starting pH.
3) The only option that indicates a 0.30 decline in pH is the second one: from 1.70 to 1.40. Therefore, that is the correct choice.
5.451 X 10³ kg of sodium carbonate is required to neutralize 5.04×10³ kg of sulfuric acid solution.
Explanation:
- Sodium carbonate neutralizes sulfuric acid (H₂SO₄). This compound is derived from a strong base (NaOH) and a weak acid (H₂CO₃). The chemical equation for this neutralization process is represented as:
Na₂CO₃ + H₂SO₄ ----> Na₂SO₄ + H₂CO₃
- The balanced equation indicates that one mole of Na₂CO₃ is needed to neutralize one mole of H₂SO₄.
- Molar mass of Na₂CO₃= 106 g/mol = 0.106 kg/mol, while Molar mass of H₂SO₄= 98 g/mol = 0.098 kg/mol.
- To neutralize 0.098 kg of H₂SO₄, the required Na₂CO₃ is 0.106 kg, thus, to neutralize 5.04×10³ kg of H₂SO₄, Na₂CO₃ needed is 5.451 X 10³ kg.
