Answer:
Amount left after 25 days = 12.5 g
Explanation:
Given data:
Mass of sample = 400 g
Half life of sample = 5 days
Mass left after 25 days = ?
Solution:
First of all we will calculate the number of half lives passes in given time period.
Number of half lives = Time elapsed / Half life
Number of half lives = 25 days/ 5 days
Number of half lives = 5
At time zero = 400 g
At 1st half life = 400 g/2 = 200 g
At 2nd half life = 200 g/2 = 100 g
At 3rd half life = 100 g/2 = 50 g
At 4th half life = 50 g/2 = 25 g
At 5th half life = 25 g/2 = 12.5 g
Answer:
4.214 × 10^23 molecules.
Explanation:
Number of molecules in a substance can be calculated by multiplying the number of moles in that substance by Avagadro's number, which is 6.02 × 10^23.
That is, no. of molecule = n × Avagadro constant
In this case, there are 0.7 moles of fructose. Hence;
number of molecules = 0.7 × 6.02 × 10^23
no. of molecule = 4.214 × 10^23 molecules.
D is the answer I believe.
Hey there!
Given the reaction:
B + H⁺ => HB⁺
At half-equivalence point : [B] = [HB⁺]
=> [B] / [HB⁺] = 1
Henderson-Hasselbalch equation :
pH = pKa + log ( [B] ) / ( HB⁺)]
pH = 14 - pKb + log ( 1 )
pH = 14 - 7.95 + 0
pH = 6.05
Answer C
Hope that helps!
Explanation:
15 8 O ---> 15 7 N + 0 1 e
Element: Oxygen
Mass Number: 16 u
Decay: Beta
238 92 U ----> 234 90 Th + -4 -2 e
Element: Uranium
Mass Number: 238.051 u
Decay: Alpha
