Elements always exist as pair of atoms called molecules .
Explanation:-
- The material which has only one types of similar atoms called element .
- Ex:-Sodium,Carbon etc
Answer:
2.2 % and 0 %
Explanation:
The equation we will be using to solve this question is:
N/N₀ = e⁻λ t
where N₀ : Number of paricles at t= 0
N= Number of particles after time t
λ= Radioactive decay constant
e= Euler´s constant
We are not given λ , but it can be determined from the half life with the equation:
λ = 0.693 / t 1/2 where t 1/2 is the half-life
Substituting our values:
λ = 0.693 / 55 s = 0.0126/s
a) For t = 5 min = 300 s
N / N₀ = e^-(0.0126/s x 300 s) = e^-3.8 = 0.022 = 2.2 %
b) For t = 1 hr = 3600 s
N / N₀ = e^-(0.0126/s x 3600 s) = 2.9 x 10 ⁻²⁰ = 0 % (For all practical purposes)
Answer:
A molecule is tetrahedral if the central atom has four bonds and no lone pairs. Explanation: ... The electron pairs in the bonds repel the electrons in the other bonds, so they all try to get as far from each other as possible.
A big black hole. I am pretty Sure that is the answer
Answer:
a) pH = 8.823
b) pH = 11.653
c) pH = 5.033
Explanation:
a) HBr is strong acid:
HBr + H2O ↔ H3O+ + Br-
∴ [ HBr ] ≅ [ H3O+ ] = 1.5E-9 M
⇒pH = -log (1.5E-9) = 8.823
b) KOH is a strong base:
KOH + H2O ↔ K+ + OH-
⇒pOH = -log [ OH- ] = -log ( 0.0045 ) = 2.346
∴ 14 = pH + pOH
⇒ pH = 14 - 2.346 = 11.653
c) conjugated base:
NH4CL + H2O ↔ HCl + NH4OH
Kb = 1.75E-5
Kw = 1E-14
⇒ Kh = Kw/Kb = 5.714E-10
∴ Kh = [ H3O+ ]² / ( 0.15 - [ H3O+ ] )......from mass balanced and load balanced
⇒ [ H3O+ ]² = (5.714E-10) * ( 0.15 - [ H3O+ ] )..... quadratic formula
⇒ [ H3O+ ] = 9.2577E-6 M
⇒ pH = -log (9.2577E-6) = 5.033
