<span>A substance is composed entirely of one type of atom, it is known as a Chemical element
because mixture contain more than one type of atom and it cannot be neutron or isotope
so correct option is B
hope it helps</span>
Answer is: concentratio of H₃O⁺ ions is 4.2·10⁻³ M.<span>
Chemical reaction: HCOOH(aq) + H</span>₂O(l) ⇄ HCOO⁻(aq) + H₃O⁺(aq).<span>
c(HCOOH) = 0,1 M.
[</span>H₃O⁺] = [HCOO⁻] = x.<span>
[HCOOH] = 0,1 M - x.
</span>Ka = [H₃O⁺] · [HCOO⁻] / [HCOOH].
0,00018 = x² / (0,1 M - x).<span>
Solve quadratic equation: x = </span>[H₃O⁺] = 0,0042 M.
Using the Henderson-Hasselbalch equation on the solution before HCl addition: pH = pKa + log([A-]/[HA]) 8.0 = 7.4 + log([A-]/[HA]); [A-]/[HA] = 4.0. (equation 1) Also, 0.1 L * 1.0 mol/L = 0.1 moles total of the compound. Therefore, [A-] + [HA] = 0.1 (equation 2) Solving the simultaneous equations 1 and 2 gives: A- = 0.08 moles AH = 0.02 moles Adding strong acid reduces A- and increases AH by the same amount. 0.03 L * 1 mol/L = 0.03 moles HCl will be added, soA- = 0.08 - 0.03 = 0.05 moles AH = 0.02 + 0.03 = 0.05 moles Therefore, after HCl addition, [A-]/[HA] = 0.05 / 0.05 = 1.0 Resubstituting into the Henderson-Hasselbalch equation: pH = 7.4 + log(1.0) = 7.4, the final pH.
Answer:check explanation
Explanation:
(a). HOW THE DISTANCE BETWEEN ELECTRON DONOR AND ACCEPTOR AFFECTS THE RATE OF ELECTRON TRANSFER IN BIOLOGICAL SYSTEM:
Distance between the acceptor and the donor can affect in two ways; short distance and long distance effect.
Short distance causes
electronic orbitals of donor and acceptor directly overlap whereas in LONG DISTANCE reactions this coupling is indirect because of
sequential overlaps of atomic orbitals of the donor, the intervening medium, and the orbitals of the acceptor.
(b). HOW REORGANIZATION ENERGY OF REDOX ACTIVE SPECIE SURROUNDING MEDIUM AFFECTS:
the reorganized energy does not depend on the pre-existing intra molecule electric field. The charge transferred inside the molecule interacts with its aqueous surroundings.
Reorganized energy can be calculated using Poisson-Boltzmann equation.
Answer:- 1.90 atm
Solution:- It is based on combined gas law equation, PV = nRT
In this equation, P is pressure, V is volume, n is moles of gas, R is universal gas constant and T is kelvin temperature.
If we divide both sides by V then:
We know that, molarity is moles per liter. So, in the above equation we could replace 
by molarity, M of the gas. The equation becomes:
P = MRT
T = 20 + 273 = 293 K
M = 
Let's plug in the values in the equation:
P = 
P = 1.90 atm
So, the pressure of the gas is 1.90 atm.
