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2 years ago

Which of the following statements is true?

Chemistry

1 answer:

lys-0071 [83]2 years ago

8 0

Answer:

Air is a good insulator because the molecules are far apart. This reduces mobility of air molecules hence conduction is difficult.

Explanation:

For other statements :

All the suns radiations are not reflected back to space because the ozone layer of the earth's atmosphere which regulates the intensity of radiations from the sun, it is transparent and porous hence heat and light rays from sun enter earth.
Work is only done by potential energy when the body is under free fall and experiencing gravitational force, but for a body moving without influence of gravity, work is done by the force applied and the distance moved by the body. This force is called a conservative force.
Total mechanical energy is given by

= Kinetic energy + Potential energy

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A sample originally contained 1.28 g of a radioisotope. It now contains 1.12 g of its daughter isotope.

dexar [7]

The answer is 3.

The relation between number of half-lives (n) and decimal amount remaining (x) can be expressed as:

 $(1/2) ^{n} =x$

We need to calculate n, but we need x to do that. To calculate what percentage of a radioactive species would be found as daughter material, we must calculate what amount remained:
1.28 - 1.12 = 0.16

If 1.28 is 100%, how much percent is 0.16:
1.28 : 100% = 0.16 : x
x = 12.5%
Presented as decimal amount:
x = 0.125

Now, let's implement this in the equation:

 $(1/2) ^{n} =0.125$

Because of the exponent, we will log both sides of the equation:
$n * log(1/2) = log(0.125)$
$n = \frac{log(0.125)}{log(1/2)}$
 $n = \frac{log(0.125)}{log(0.5)}$
 $n= \frac{-0.903}{-0.301}$
$n = 3$

Therefore, 3 half-lives have passed since the sample originally formed.

4 0

3 years ago

Read 2 more answers

calculate the volume of air in liters that you might inhale(and exhale)in 8.0 hours. Assume that each breath has a volume of 0.5

maks197457 [2]

Formula:
0.57 liters = 1 breath(17 breaths = 1minute)(60 minutes = 1 hour)(8 hours) = 4651.2 liters

each breath is 0.57 liters
He or she exhales 17(0.57) = 9.69 liters in a minute
in an hour, he or she exhales 9.69(60) liters in a minute = 581.4 liters
Answer = in 8 hours he or she exhales, 581.4(8) = 4651.2 liters in 8 hours

Hope that answers your question!!!!have a great day!!!

6 0

3 years ago

Which of the following pairs of aqueous solutions produce a precipitate?

dolphi86 [110]

Answer:

NaCi + LiCl is the correct answer

6 0

2 years ago

Why did Democritus disagree with Aristotle?

posledela

Answer:

Aristotle rejected Democritus's concept of the atom, as it did not agree with his own ideas on nature!

3 0

2 years ago

Read 2 more answers

In which reaction do four total molecules of reactants produce two total molecules of products?

Pachacha [2.7K]

Answer:

option D = N₂ + 3H₂ → 2NH₃

Explanation:

The reaction in which the nitrogen and hydrogen are reacted to form the ammonia is true.

N₂ + 3H₂ → 2NH₃

In this reaction we can see that one molecules of nitrogen react with three molecules of hydrogen and form two molecules of ammonia.

while the other options are in correct because,

2SO₂ + O₂ → 2SO₃

In this reaction two molecules of SO₂ react with one molecule of oxygen and form two molecules of SO₃.

2H₂S + 3O₂ → 2SO₂ + 2H₂O

In this reaction two molecules of H₂S react with three molecules of oxygen and produced four molecules of product.

SnO₂ + 2H₂ → Sn + 2H₂O

This is also incorrect because three molecules of reactant form three molecules of product.

5 0

2 years ago