Answer:
Option 4 is correct (72 seconds)
Explanation:
Option 4 is correct (72 seconds)
The formula we are going to use is:

Where:
A is the final concentration
A_o is the initial concentration
k is the constant
t is the time
Half-Life=0.693/k
Half-life in our case=24 seconds
k=0.693/24
k=0.028875 s^-1
Since the concentration is decreased by 87.5 % which means only 12.5%(100-87.5%) is left.
The ratio
will become 0.125

t≅ 72 seconds
I think the answer is b hope this helps
Answer:
0.0073 g
Explanation:
Considering:
Or,
Given :
For HCl :
Molarity = 0.010 M
Volume = 25 mL
The conversion of mL to L is shown below:
1 mL = 10⁻³ L
Thus, volume = 25×10⁻³ L
Thus, moles of HCl :
Moles of HCl = 0.00025 moles
Considering the reaction shown below as:-

2 moles of HCl reacts with 1 mole of 
So,
1 moles of HCl reacts with 1/2 mole of 
Also,
0.00025 moles of HCl reacts with
mole of 
Mole of
= 0.000125 moles
Molar mass of
= 58.3197 g/mol
Mass = Moles*Molar mass =
= 0.0073 g
So Helium walks into a bar and orders a beer...
The bartender says, "Sorry we don't serve noble gases here."
Helium doesn't react.