B. The energy barrier between reactants and products
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Answer : The value of rate constant is, 
Explanation :
First we have to calculate the rate constant, we use the formula :
Expression for rate law for first order kinetics is given by:
where,
k = rate constant = ?
t = time passed by the sample = 20 min
a = let initial amount of the reactant = 100 g
a - x = amount left after decay process = 100 - 85 = 15 g
Now put all the given values in above equation, we get
Therefore, the value of rate constant is,
Since, the options have not been given the question is incomplete.
What is Darwin's name for species that do not appear to have changed for millions of years?
a.
Dinosaurs
b.
Living fossils
c.
Old souls
d.
Ancient moderns
Answer: b. Living fossil
Explanation:
In 1859 Charles Darwin proposed the term living fossil, that means a species or group of species that had not changed in terms of evolutionary context thus can be useful in tracing the extinct or previously existing forms of life. The examples of the living fossils are horseshoe crabs, ginkgo (Conifers) and tuatara. These group of animals were existed unchanged in the Ordovician, Permian, and Triassic periods respectively with few surviving species.
Answer:
Answer B) 4.2x10^17
Explanation:
To produce the reaction 3 using reaction 1 and 2 we need to invert the order of the first reaction the second in the same order, as it's shown:
____________________________
Due to the inversion of the first equation, the equilibrium constant of the new reaction is K1'=1/K1.=2.4x10^30
Finally, the new equilibrium constant K3 is the product of the previous constants:
K3=K1'*K2=4.2x10^17
Answer:
176.36g/mol
Explanation:
It was given that:
Mass of ascorbic acid=0.552 g
Volume of water=20.0 mL
Concentration of KOH=0.1103 M
Volume of KOH=28.42 mL. = 0.02842l
pH of solution at 10.0 mL= 3.72
At equivalence point, number of moles of acid is equal to the number of moles of base.
Number of moles of base= (KOH) x Volume
=0.1103 x 0.02842 L
=0.00313 moles.
Therefore number of miles of acid= 0.00313moles
No of moles= Mass/molar mass
Molar Mass= Mass of Acid/ No of moles of acid
= 0.552g/0.00312moles
= 176.36g/mol
