Ask question

Ask question

All categories

4 years ago

9

Alexandra knows that the atomic number of the element potassium, K, is 19. She also knows that one particular isotope of potassi

um has a mass number of 39. How many neutrons can be found in the nucleus of this isotope of potassium?
A) 19

B) 20

C) 39

D) 58

1 answer:

fiasKO [112]4 years ago

8 0

I believe the answer is 58 but I’m not sure

You might be interested in

PLEASE HELP ASAP

emmainna [20.7K]

Aluminum comes from several sources; it rarely occurs in pure form in nature, and is most frequently found embedded in other minerals, primarily bauxite. This would be most commonly found in the dirt.

4 0

3 years ago

Read 2 more answers

The half-life of plutonium 239 is 24,200 years. Assume that the decay rate is proportional to the amount. Determine the amount o

kotykmax [81]

Answer:

time taken is equal to 14,156 years

Explanation:

we know,

$Y=Ae^{-kt}$

at t = 0

Y(0) = A

given that half life of plutonium 239 = 24,200

$\dfrac{A}{2}=Ae^{-kt}\\0.5=e^{-kt}\\k\times 24200 = ln(2)\\k = \dfrac{ ln(2)}{24200}$

$Y=Ae^{-kt}$

$\frac{3}{2} = e^{-kt}\\ln(1.5)=-\dfrac{ ln(2)}{24200}\times t\\t=-\dfrac{ln(1.5)\times 24200}{ ln(2)}\\t=14,156 \ years$

hence time taken is equal to 14,156 years

5 0

3 years ago

Choose the correct statement regarding projectile motion in the absence of air resistance. Assume the object is at sea level mov

pishuonlain [190]

Answer:

Explanation:

The magnitude of the acceleration in the x direction is always zero: TRUE.

At the apex, in the y direction the velocity is zero and the accelration is positive. TRUE.

At the apex, in the x direction, the velocity is zero and the acceleration is zero. FALSE. The accelration is zero, but the velocity is the same it had when it was shot.

The magnitude of the velocity in the y direction is always constant. FALSE, it's subject to gravity and it's velocity varies as $v=v_0 - 9.81ms^{-2} t$

At the apex, in the Y direction, the velocity is negative and the acceleration is zero. FALSE. Velocity is zero, Acceleration is $9.81 ms^{-2}$ , towards the negative y axis

7 0

3 years ago

ANSWER FAST FOR BRAINLIEST!

Ne4ueva [31]

Answer:

the last one

Explanation:

7 0

3 years ago

Read 2 more answers

I’m confused on this worksheet can someone help

Finger [1]

Answer:

well for C the horse is at rest at 10 to 15

D is 0 to 10

E is 15 to 25

Explanation:

If you search up examples it will help with this worksheet.

If I am work then I appologize

5 0

3 years ago