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2 years ago

. When a newspaper is left in direct sunlight for a few days, the paper begins to turn yellow. The yellow

Chemistry

1 answer:

34kurt2 years ago

6 0

Physical Change

It is being changed by the sun

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The isotope 239 Pu 94 has a half life of 24,400 years. If a sample of nuclear waste originally contained 12kg of 239 Pu 94, how

Natasha2012 [34]

Equation for half-lives:

Nt = No x (1/2)^n

No = initial amount
Nt = final amount after t years
n = number of half lives = t/(single half-life)
t = years

Nt = 3/12 = 0.25
No = 12/12 = 1.00
n = t/(24400)

3/12 = (12/12) x (0.5)^(t/24400)
(0.25) = 1.00 x (0.5)^(t/24400)
0.25/1.00 = 0.5^(t/24400)
ln(0.25) = ln(0.5^(t/24400))
ln(0.25) = (t/24400)*ln(0.5)
ln(0.25)/ln(0.5) = (t/24400)
2 = t/24400
2*24400 = t
t = 48800 yrs

answer is t = 48,800 yrs

5 0

3 years ago

How many grams of sucrose would you add to water to make a total of 2.1 L of 9 % solution (mass per volume)? Make your answer's

s344n2d4d5 [400]

Answer : The mass of sucrose added to water will be, 189.0 grams.

Explanation :

As we are given that 9 % solution (mass per volume) that means 9 grams of sucrose present in 100 mL volume of solution.

Total given volume of solution = 2.1 L = 2100 mL (1 L = 1000 mL)

Now we have to determine the mass of sucrose in solution.

As, 100 mL of solution contains 9 grams of sucrose

So, 2100 mL of solution contains $\frac{2100mL}{100mL}\times 9g=189.0$ grams of sucrose

Therefore, the mass of sucrose added to water will be, 189.0 grams.

8 0

3 years ago

B) calculate the ratio of moles of h2o to moles of anhydrous kal(so4)2. note: report the ratio to the closest whole number. (sho

Sindrei [870]

Answer: -

Mass of Hydrated KAl(SO₄)₂ = 2.0 g

Molar mass of anhydrous KAl(SO₄)₂ = 258.20 g/ mol

Mass of of anhydrous KAl(SO₄)₂ = mass of the 2nd heating = A

The mass of water released = mass of the Aluminum Cup + 2.0 grams of KAl(SO₄)₂ - mass of the 2nd heating

= H g

Moles of water released = $\frac{H g}{18 g/mol}$

Moles of anhydrous KAl(SO₄)₂ = $\frac{A g}{258.20 g/mol}$

Required ratio = $\frac{moles of water}{moles of anhydrous KAl(SO4)2}$

5 0

3 years ago

Which statement correctly describes compounds? Compounds cannot be broken down into simpler substances by chemical means. Each c

77julia77 [94]

The answer is: each compound is composed of one type of molecule.

8 0

3 years ago

Read 2 more answers

Electrons are emitted from a conductor when the conductor is

alina1380 [7]

Well, I have personally used both A and C (provided the light frequency takes it above the work function of the condutor).

D could also work - a good conductor subject to a small voltage will carry a very large current. For instance, a flashlightg bulb filament is hot enough to emit electrons.

B is a no go.

7 0

3 years ago