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3 years ago

The population of the world nearly doubled between the years of 1965 and 2000.

1 answer:

3 0

True. The world population in 1965 was 3.324 billion . In 2000 the world population was 6.115 billion. The difference is 2.791.

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A binding protein binds to a ligand l with a kd of 400 nm what is the concentration of ligand when y is 0.25

vampirchik [111]

Answer:

The answer is 7600 nm.

Explanation:

As, Y = 0.25 = [ L ÷ (400 + (L)]

0.95 x 400 + 0.25 [ L] = [ L ]

380.25 = [ L ] - 0.95 [ L ]

= 0.05 [L]

[L] = 380 ÷ 0.05 = 7600nm

6 0

3 years ago

Which of the following symbolic representations of matter signifies a mixture of elements?

andreev551 [17]

D only..

A is pure compound
B is mixture of compound and element
C is mixture of compounds
D is mixture of elements

7 0

3 years ago

If 20.0 grams of Al is placed into a solution containg

meriva

Answer:

m H2(g) = 2.241 g H2(g)

Explanation:

2Al(s) + 3H2SO4(aq) → Al2(SO4)3(aq) + 3 H2(g)

limit reagent:

∴ Mw Al = 26.982 g/mol

∴ Mw H2SO4 = 98.0785 g/mol

⇒ n Al = (20 g Al)×(mol/26.982 g) = 0.7412 mol Al

⇒ n H2SO4 = ( 115 g H2SO4 )×(mol/98.0785 g) = 1.173 mol H2SO4

⇒ n H2 = (0.7412 mol Al)×(3 mol H2/ 2 mol Al) = 1.112 mol H2

∴ Mw H2 = 2.016 g/mol

⇒ g H2 = (1.112 mol H2)×(2.016 g/mol) = 2.241 g H2

5 0

3 years ago

1. In the models, what particles do the colored and plain sesame seeds represent? What particles do the poppy seeds represent

Veronika [31]

Ok the answers to the hole .doc is
1. Neutrons, Protons, and Electrons
2. N<span>ucleus
3. N</span>eutrons and Protons
4. Electrons
5. Because they represent different things (I would put this in your own words)

6 0

3 years ago

Read 2 more answers

Measurements show that unknown compound has the following composition: element mass 38.7 % calcium, 19.9 % phosphorus and 41.2 %

Mademuasel [1]

Answer:

D) empirical formula is: C₃P₂O₈

Explanation:

Given:

Mass % Calcium (Ca) = 38.7%

Mass % Phosphorus (P) = 19.9%

Mass % oxygen (O) = 41.2 %

This implies that for a 100 g sample of the unknown compound:

Mass Ca = 38.7 g

Mass P = 19.9 g

Mass O = 41.2 g

Step 1: Calculate the moles of Ca, P, O

Atomic mass Ca = 40.08 g/mol

Atomic mass P = 30.97 g/mol

Atomic mass O = 16.00 g/mol

$Moles\ Ca = \frac{38.7g}{40.08g/mol} =0.966\ mol\\\\Moles\ P = \frac{19.9g}{30.97g/mol} =0.643\ mol\\\\Moles\ O = \frac{41.2g}{16.00g/mol} =2.58\ mol$

Step 2: Calculate the molar ratio

$C = \frac{0.966}{0.643} =1.50\\\\P = \frac{0.643}{0.643} = 1.00\\\\O = \frac{2.58}{0.643} =4.00$

Step 3: Calculate the closest whole number ratio

C: P: O = 1.50 : 1.00 : 4.00

C : P : O = 3:2:8

Therefore, the empirical formula is: C₃P₂O₈

7 0

3 years ago