Q1.

Sodium-25 was to be used in an experiment, but it took 3.0 minutes to get the sodium from the reactor to the laboratory. If 8.0

Ksenya-84 [330]

Sodium-25 after 3 minutes : 1.0625 mg

<h3>Further explanation</h3>

General formulas used in decay:

$\large{\boxed{\bold{N_t=N_0(\dfrac{1}{2})^{t/t\frac{1}{2} }}}$

T = duration of decay

t 1/2 = half-life

N₀ = the number of initial radioactive atoms

Nt = the number of radioactive atoms left after decaying during T time

<h3 />

No=8 mg

t1/2=60 s

T=3 min=180 s

$\tt Nt=No\dfrac{1}{2}^{T/t1/2}\\\\Nt=8.5\dfrac{1}{2}^{180/60}\\\\Nt=8.5(\dfrac{1}{2})^3\\\\Nt=1.0625~mg$

5 0

3 years ago

An area where material from deep within Earth's mantle rises to the crust and melts to form magma is called a

AnnyKZ [126]

Answer:

centro of the eqrhtjrurjfjrnfbfn

6 0

3 years ago

Which reaction will occur? 2NaBr+I2 —> 2NaI + Br2

Veronika [31]

Answer:

This is a single replacement reaction because I replaces Br.

7 0

4 years ago

Read 2 more answers

How did humans and animals adapt/survive to hurricane Katrina? AND Give examples of organisms that could not adapt/survive? PLS

guajiro [1.7K]

Some organisms that could not survive where cats, dogs, birds, horses, fish, cows, every animal that was in hurricane Katrina was affected by it. Some of these animals were able to survive and others were rescued from near death.
Most of the animals could not adapt to this change because they are not used to this type of change. The water was too strong for the fish and when the water brought the fish into any water/sea animal there was also medal because the water in through peoples houses (pretty much the man-made stuff that's not meant for sea is killing the animals in the water).
Any animal that was left behind was affected. The animals could not adapt to this change they have never experienced something that tragic before, how they survived? Well, the animals that survived was mainly because of there natural instinct, before an earthquake or anything hits there are many animals that can sense the storm coming before it even hits and in this situation, the animal could, wake up, run to owner, flee, run to higher ground, and if they cant sense it. They see whats going on around them and then they know something is wrong.

8 0

4 years ago

Read 2 more answers

You are instructed to create 900. mL of a 0.29 M phosphate buffer with a pH of 7.8. You have phosphoric acid and the sodium salt

Aleksandr [31]

Answer:

B and C

Explanation:

When we have to do a buffer solution we always have to choose the reaction that has the <u>pKa closer to the desired pH value</u>. When we find the pKa values we will obtain:

$pKa_1=-Log[6.9x10^-^3]=2.16$

$pKa_2=-Log[6.2x10^-^8]=7.20$

$pKa_3=-Log[4.8x10^-^13]=12.31$

The closer value is pKa2 with a value of 7.2. Therefore we have to use the second reaction. In which $H_2PO_4^-^1$ is the <u>acid</u> and $HPO_4^-^2$ is the <u>base</u>. Therefore the answer for the first question is B and the answer for the second question is C.

8 0

3 years ago