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3 years ago

Cells can regulate different processes in two ways. They can turn on and off the genes that make enzymes, or they can

Chemistry

1 answer:

scoundrel [369]3 years ago

3 0

Answer:

im pretty sure its d

Explanation:

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To aid in the prevention of tooth decay, it is recommended that drinking water contains 0.900 ppm fluoride (F-). A) How many g o

Romashka-Z-Leto [24]

Answer:

a) <u>1.740 g</u> of F- must be added to a cylindrical water reservoir

b) Grams of sodium fluoride, NaF, that contain this much fluoride:

3.84 g

Explanation:

Step 1. calculate the volume of the tank:

Volume of cylinder =

$\pi r^{2}h$ ,

Here r = radius of the cylinder = d/2

h = depth = 21.80m

$r=\frac{d}{2}$

$=\frac{3.36x10^{2}}{2}$

= 168 m

Volume =

$=\frac{22\times 168^{2}\times 21.80}{7}$

$=1.93\times 10^{6} m^{3}$

2.Convert ppm to g/m3 and Solve for mass of F-

$1ppm = 1g/m^{3}$

$0.9ppm = 0.9g/m^{3}$

Because both ppm and g/m3 are same quantity .

$g/m^{3} =\frac{mass\ of\ F-(g)}{Volume\ m^{3}}\times 10^{6}$

$0.9 =\frac{mass\ of\ F-}{1.93\times 10^{6} m^{3}}\times 10^{6}$

$mass\ of\ F- =1.740g$

mass of F- required = 1.740 g

3. Apply <u>mole concept </u>to calculate grams of sodium fluoride produced

mass of 1 mole of F2 = 38 g

mass of 1 mole of NaF = 42 g

(from periodic table calculate molar mass)

$2Na+F_{2}\rightarrow 2NaF$

Here 1 mole of F2 produce = 2 mole of NaF

So,

38 g of F2 produce = 2 x 42 g of NaF

38 g of F2 produce = 84 g of NaF

1 g of F2 produce = 84/38 g of NaF

1.74 g F2 produce =

$\frac {84}{38}\times 1.74$

1.74 g F2 produce = 3.84 g of NaF

3.84 g of NaF is produced

3 0

3 years ago

In the reaction, H2SO4. +. H2O -------> HSO4- +. H3O+ The Base is ____________ a H2SO4 b H3O+ c H2O d HSO4-

expeople1 [14]

The base is H2O because it is accepting an H+ ion.

5 0

3 years ago

The kinetic energy of a ball with a mass of 0.5 kg and a velocity of 10 m/s is

Art [367]

Hi! Well the formula of kinetic energy is Ke = 0.5 x M x V^2
0.5 x 0.5 x 10^2
0.25 x 20
5 J (joule)

5 0

4 years ago

What determines the order of placement of the elements on the modern Periodic Table?

Pachacha [2.7K]

The order of placement of the elemnts on the modern Periodic Table is determinated by:
1)atomic number (Z=number of protons).

3 0

4 years ago

Read 2 more answers

Sodium hydroxide is available commercially as a 50.0% by weight aqueous solution. The density of the solution is 1.53 g/mL. Calc

bulgar [2K]

Answer:

[NaOH] = 19.1 M

Last option.

Explanation:

Sodium hydroxide is available commercially as a 50.0% by weight aqueous solution.

50% by weight means, that in 100 g of solution we have 50 grams of solute.

Molar mass of solute: 40 g/m

Mass / Molar mass = moles

50 g / 40 g/m = 1.25 moles

These are the moles of solute in 100 grams of solution, so we must use density data, so we can find out our volume.

Solution density = Solution mass / Solution volume

1.53 g/mL = 100 g / Solution volume

Solution volume = 100 g / 1.53 g/mL

Solution volume = 65.3 mL

1.25 moles of solute are in 65.3 mL of solution

Molarity = moles /L

Let's convert 65.3 mL in L

65.3 / 1000 = 0.0653 L

1.25 moles /0.0653 L = 19.1 M

3 0

4 years ago