Answer:
The answer to your question is letter D.
Explanation:
A. Has a fixed volume This is not the right answer, liquids and gases take the shape of the container in which they are.
B. Particles stay in a fixed position This answer is wrong, this characteristic is of solids but not of liquids and gases.
C. No particle movement This characteristic is also of solids, in liquids and gases the particles can move.
D. Takes the shape of the container. This is the right answer, liquids and gases take the shape of the container.
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.
The Earths Surface, it’s also known as the troposphere also dense* lol
Atoms of different elements can be identical