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Papessa [141]
3 years ago
5

Significant figures

Chemistry
1 answer:
Sergeu [11.5K]3 years ago
4 0

Answer:

go look for that on google

Explanation:

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Why do scientists think there is an undiscovered carbon sink somewhere?
dedylja [7]
The major carbon sources (reservoirs that release more carbon than absorbed) are: deforestation and fossil fuels

The major carbon sinks (reservoirs that absorb more carbon than released) are:
soil, oceans and plants.

When scientists calculate the amount of carbon dioxide is returned to the atmosphere vs the released the amount of carbon, a large amount is unaccounted for and the total does not add up. This is why scientists believe there is an undiscovered carbon sink somewhere.
6 0
3 years ago
Read 2 more answers
Please I need help on these 3 questions. Thank You.​
Liula [17]

1.

V = 200 mL (volume)

c = 3 M = 3 mol/L (concentration)

First we convert mL to L:

200 mL = 0.2 L

Then we calculate the moles using the formula: n = V × c = 0.2 L × 3 mol = 0.6 mol

Finally, we just use the molar mass of CaF2 to calculate the actual mass:

molar mass = 78 g/mol

The formula is: m = n × mm (mass = moles × molar mass)

m = 0.6 mol × 78 g/mol = 46.8 g

2.

For this question the steps are exactly like the first question.

V = 50mL = 0.05 L

c = 12 M = 12 mol/L

n = V × c = 0.05 L × 12 mol/L = 0.6 mol

molar mass (HCl) = 36.5 g/mol

m = n × mm = 0.6 mol × 36.5 g/mol = 21.9 g.

3.

The steps for this question are the opposite way.

m(K2CO3) = 250 g

molar mass = 138 g/mol

n = m ÷ mm = 1.81 mol

c = 2 mol/L

V = n ÷ c = 1.81 mol ÷ 2 mol/L = 0.905 L = 905 mL

6 0
3 years ago
You have a radioactive isotope with a mass of 400 grams. The sample has a half life of 5 days. How much is left after 25 days ha
Alexeev081 [22]

Answer:

Amount left after 25 days = 12.5 g

Explanation:

Given data:

Mass of sample = 400 g

Half life of sample = 5 days

Mass left after 25 days = ?

Solution:

First of all we will calculate the number of half lives passes in given time period.

Number of half lives = Time elapsed / Half life

Number of half lives = 25 days/ 5 days

Number of half lives = 5

At time zero = 400 g

At 1st half life = 400 g/2 = 200 g

At 2nd half life = 200 g/2 = 100 g

At 3rd half life = 100 g/2 = 50 g

At 4th half life = 50 g/2 = 25 g

At 5th half life = 25 g/2 = 12.5 g

4 0
3 years ago
Add coefficients to balance the equation to make water.<br> H2(g) +O2 (g)H20 (1)
OLEGan [10]

Answer:

2H2+2O2=2H2O

Explanation:

hope this helps

6 0
3 years ago
What is the definition of a chemical bond?
Makovka662 [10]

A thing used to tie something or to fasten things together.

"she brushed back a curl that had strayed from its bonds"

OR

An agreement with legal force, in particular.

5 0
3 years ago
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