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KiRa [710]
2 years ago
13

(Physical Science)

Chemistry
1 answer:
Vera_Pavlovna [14]2 years ago
4 0
Alkaline earth metals
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What is the half-life of 20 g of a radioactive sample if 5 g remain after 8 minutes?
Anni [7]

Hello!

The half-life is the time of half-disintegration, it is the time in which half of the atoms of an isotope disintegrate.

We have the following data:

mo (initial mass) = 20 g

m (final mass after time T) = 5 g

x (number of periods elapsed) = ?

P (Half-life) = ? (in minutes)

T (Elapsed time for sample reduction) = 8 minutes

Let's find the number of periods elapsed (x), let us see:

m =  \dfrac{m_o}{2^x}

5 =  \dfrac{20}{2^x}

2^x = \dfrac{20}{5}

2^x = 4

2^x = 2^2

\boxed{x = 2}


Now, let's find the half-life (P) of the radioactive sample, let's see:

T = x*P

8 = 2*P

2\:P = 8

P = \dfrac{8}{2}

\boxed{\boxed{P = 4\:minutes}}\Longleftarrow(Half-Life)\end{array}}\qquad\checkmark

I Hope this helps, greetings ... DexteR! =)

5 0
3 years ago
Write and balance an equation for the following reaction. Identify the type of reaction.
Strike441 [17]

Answer: Synthesis/ Combination

reaction

4 Al + 3S2 => 2 Al2S3

Explanation: The equation is now balanced the amount of each individual atom in both the reactant and product sides are equal.

8 0
3 years ago
Which is an acceptable Lewis structure for a diatomic nitrogen molecule?
timofeeve [1]
Nitrogen has 5 valence electrons (ve-), so a diatomic nitrogen molecule will have twice as many, 10 valence electrons. Then, just draw electrons in pairs of 2 until you both get ride of all of them (reach 0) and you fill every atom (eight electrons each). It can be drawn either way, the important thing is that there are 3 electron pairs shared between the two atoms.

6 0
3 years ago
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Which example is a trace fossil? {A} dinosaur egg {B} dinosaur footprint {C} dinosaur bone {D} shark tooth
viktelen [127]

dinosaur footprint

Explanation:

A dinosaur footprint is an example of a trace fossil. A trace fossil is a type of fossil that shows the activities of organisms that lived in the past.

  • Fossils are the preserved remains of organisms that lived several years ago.
  • Fossils are usually found in sedimentary rocks and thick layers of ice in temperate and polar regions.
  • Body fossils are the remains of the body parts of an organism that has been preserved. They can be skeletal parts, teeth, eggs e.t.c
  • A trace fossil shows the preserved remains of the activities of an organism.
  • They can be fingerprints, burrows and borings, feccal pellets e.t.c

Learn more":

fossils and evolution brainly.com/question/12790206

#learnwithBrainly

5 0
3 years ago
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1,670,000,000 in<br> scientific notation pleaseeee
noname [10]

Answer:

1.67 × 10^9

Explanation:

6 0
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