Answer:
Normality N = 0.2 N
Explanation:
Normality is the number of gram of equivalent of solute divided of volume of solution, where the number of gram of equivalent of solute is weight of the solute divided by the equivalent weight.
Normality is represented by N.
Mathematically, we have :

Given that:
number of gram of equivalent of solute = 90 milliequivalents 90 × 10⁻³ equivalent
volume of solution (HCl) = 450 mL 450 × 10⁻³ L

Normality N = 0.2 N
The initial concentration of the unknown acid is 0.1900 M.
Explanation:
Titration is a chemical method of analysis to know the concentration and volume of the unknown chemical or analyte.
The formula for the titration is:
Macid x Vacid = Mbase x V base
The volume must be in litres. The volume is given in ml it should be divided with 1000 to obtain values in litre.
Data given are:
volume of acid= 10 ml 0.01 L
Molarity of the acid = ?
volume of the NaOH or base = 15.4 ml or 0.0154 L (equivalence point of the base)
molarity of the base = 0.1234 M
Applying the formula and putting the values, we get
Macid x 0.01 = 0.1234 x 0.0154
Macid = 0.1900 M
The weak acid is having molarity of 0.1900 M against the strong base with molarity of 0.1234M.
Direct electron transfer from a a singlet reduced species to a triplet oxidizing species is quantum-mechanically forbidden.
<h3><u>Transfer from singlet to triplet:</u></h3>
- Either an excited singlet state or an excited triplet state will occur when an electron in a molecule with a singlet ground state is stimulated (through radiation absorption) to a higher energy level.
- All electron spins in a molecule electronic state known as a singlet are coupled.
- In other words, the ground state electron and the stimulated electron's spin are still coupled (a pair of electrons in the same energy level must have opposite spins, per the Pauli exclusion principle).
- The excited electron and ground state electron are parallel in a triplet state because they are no longer coupled (same spin).
- It is less likely that a triplet state would arise when the molecule absorbs radiation since excitation to a triplet state necessitates an additional "forbidden" spin transfer.
To view more questions on quantum mechanism, refer to:
brainly.com/question/13639384
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Picoliter is a unit of measurement for liquids.
One picoliter = 1×10⁻⁹ mililiters
So:
19 mL ---- x pL
1×10⁻⁹ mL ---- 1 pL
1×10⁻⁹x = 19
x = 1,9 × 10¹⁰ pL
or 19,000,000,000 pL
Answer: 1.9 × 10¹⁰ pL