Answer : The time required for decay is, 84 days.
Explanation :
Half-life of chromium-51 = 28 days
First we have to calculate the rate constant, we use the formula :



Now we have to calculate the time required for decay.
Expression for rate law for first order kinetics is given by:

where,
k = rate constant
t = time taken by sample = ?
a = let initial activity of the sample = 100
a - x = amount left after decay process = 12.5
Now put all the given values in above equation, we get


Therefore, the time required for decay is, 84 days.
Answer:
true
Explanation:
A single replacement reaction is a reaction that an element is displaced with another element in a compound
A+BC------AC+B
Mg+2HCl-------MgCl2+H2
Answer:
A 50-mL volumetric cylinder with 0.1-mL accuracy scale should be used for this purpose since three significant figures of accuracy are required.
Explanation:
Hello,
A 50-mL volumetric cylinder with 0.1-mL accuracy scale should be used for this purpose since three significant figures of accuracy are required.
Best regards.
Molar mass of NH_3



We know.
No of moles=Given mass/Molar mass


Now
Lets write the balanced equation

- There is 2moles of Ammonia
- 3moles of H_2
- 1mole of N_2
Now

For Hydrogen



For Ammonia



For Nitrogen


Answer: I believe the answer is 12
Explanation: